gh-35295: put the actual description first in issue templates

    
...so that relevant information appears when hovering over items of the
issue list, and so that one can read the actual issue on the issue page
without scrolling over a full page of boilerplate.

Also remove the title from the Description section of the PR template
(same rationale).

Any opinions on that?

<!-- ^^^^^
Please provide a concise, informative and self-explanatory title.
Don't put issue numbers in there, do this in the PR body below.
For example, instead of "Fixes #1234" use "Introduce new method to
calculate 1+1"
-->
### 📚 Description

<!-- Describe your changes here in detail -->
<!-- Why is this change required? What problem does it solve? -->
<!-- If it resolves an open issue, please link to the issue here. For
example "Closes #1337" -->

### 📝 Checklist

<!-- Put an `x` in all the boxes that apply. -->
<!-- If your change requires a documentation PR, please link it
appropriately -->
<!-- If you're unsure about any of these, don't hesitate to ask. We're
here to help! -->

- [x] I have made sure that the title is self-explanatory and the
description concisely explains the PR.
- [ ] I have linked an issue or discussion.
- [ ] I have created tests covering the changes.
- [ ] I have updated the documentation accordingly.

### ⌛ Dependencies
<!-- List all open pull requests that this PR logically depends on -->
<!--
- #xyz: short description why this is a dependency
- #abc: ...
-->
    
URL: #35295
Reported by: Marc Mezzarobba
Reviewer(s): Dima Pasechnik, Marc Mezzarobba, Tobias Diez

.github/ISSUE_TEMPLATE/bug_report.yml

@@ -3,33 +3,11 @@ description: Report a bug
 title: "<title>"
 labels: "t: bug"
 body:
-  - type: checkboxes
-    attributes:
-      label: Is there an existing issue for this?
-      description: Please search to see if an issue already exists for the bug you encountered.
-      options:
-      - label: I have searched the existing issues for a bug report that matches the one I want to file, without success.
-        required: true
-  - type: checkboxes
-    attributes:
-      label: Did you read the documentation and troubleshoot guide?
-      description: Please read [README.md](https://github.com/sagemath/sage/blob/develop/README.md) and [the Troubleshooting section in the Installation Guide](https://doc.sagemath.org/html/en/installation/troubles.html).
-      options:
-      - label: I have read the documentation and troubleshoot guide
-        required: true
-  - type: textarea
+  - type: markdown
     attributes:
-      label: Environment
-      description: |
-        examples:
-          - **OS**: Ubuntu 20.04
-          - Sage Version: 9.2
       value: |
-          - **OS**:
-          - **Sage Version**: 
-      render: markdown
-    validations:
-      required: true
+        * Please search to see if an issue already exists for the bug you encountered.
+        * Please read [README.md](https://github.com/sagemath/sage/blob/develop/README.md) and [the Troubleshooting section in the Installation Guide](https://doc.sagemath.org/html/en/installation/troubles.html).
   - type: textarea
     attributes:
       label: Steps To Reproduce
@@ -60,3 +38,24 @@ body:
         Links? References? Anything that will give us more context about the issue you are encountering!
     validations:
       required: false
+  - type: textarea
+    attributes:
+      label: Environment
+      description: |
+        examples:
+          - **OS**: Ubuntu 20.04
+          - Sage Version: 9.2
+      value: |
+          - **OS**:
+          - **Sage Version**:
+      render: markdown
+    validations:
+      required: true
+  - type: checkboxes
+    attributes:
+      label: Checklist
+      options:
+      - label: I have searched the existing issues for a bug report that matches the one I want to file, without success.
+        required: true
+      - label: I have read the documentation and troubleshoot guide
+        required: true

.github/ISSUE_TEMPLATE/failure_building_from_source.yml

@@ -4,20 +4,11 @@ title: "<title>"
 labels: ['c: build', 't: bug']
 assignees: []
 body:
-  - type: checkboxes
+  - type: markdown
     attributes:
-      label: Is there an existing issue for this?
-      description: Please search to see if an issue already exists for the bug you encountered.
-      options:
-      - label: I have searched the existing issues for a bug report that matches the one I want to file, without success.
-        required: true
-  - type: checkboxes
-    attributes:
-      label: Did you read the documentation and troubleshoot guide?
-      description: Please read [README.md](https://github.com/sagemath/sage/blob/develop/README.md) and [the Troubleshooting sectionin the Installation Guide](https://doc.sagemath.org/html/en/installation/troubles.html).
-      options:
-      - label: I have read the documentation and troubleshoot guide
-        required: true
+      value: |
+        * Please search to see if an issue already exists for the bug you encountered.
+        * Please read [README.md](https://github.com/sagemath/sage/blob/develop/README.md) and [the Troubleshooting section in the Installation Guide](https://doc.sagemath.org/html/en/installation/troubles.html).
   - type: textarea
     attributes:
       label: Environment
@@ -65,3 +56,11 @@ body:
         Links? References? Anything that will give us more context about the issue you are encountering!
     validations:
       required: false
+  - type: checkboxes
+    attributes:
+      label: Checklist
+      options:
+      - label: I have searched the existing issues for a bug report that matches the one I want to file, without success.
+        required: true
+      - label: I have read the documentation and troubleshoot guide
+        required: true

.github/ISSUE_TEMPLATE/feature_report.yml

@@ -3,13 +3,10 @@ description: Suggest an idea
 title: "<title>"
 labels: "t: enhancement"
 body:
-  - type: checkboxes
+  - type: markdown
     attributes:
-      label: Is there an existing issue for this?
-      description: Please search to see if an issue already exists for the bug you encountered.
-      options:
-      - label: I have searched the existing issues for a bug report that matches the one I want to file, without success.
-        required: true
+      value: |
+        * Please search to see if an issue already exists for the bug you encountered.
   - type: textarea
     attributes:
       label: Problem Description
@@ -34,3 +31,9 @@ body:
       description: Add any other context about the problem here.
     validations:
       required: false
+  - type: checkboxes
+    attributes:
+      label: Is there an existing issue for this?
+      options:
+      - label: I have searched the existing issues for a bug report that matches the one I want to file, without success.
+        required: true

.github/PULL_REQUEST_TEMPLATE.md

@@ -1,17 +1,20 @@
-<!-- Please provide a concise, informative and self-explanatory title. -->
-<!-- Don't put issue numbers in the title. Put it in the Description below. -->
-<!-- For example, instead of "Fixes #12345", use "Add a new method to multiply two integers" -->
-
-### :books: Description
+<!-- ^^^^^
+Please provide a concise, informative and self-explanatory title.
+Don't put issue numbers in there, do this in the PR body below.
+For example, instead of "Fixes #1234" use "Introduce new method to calculate 1+1"
+-->
+<!-- Describe your changes here in detail -->
 
-<!-- Describe your changes here in detail. -->
 <!-- Why is this change required? What problem does it solve? -->
 <!-- If this PR resolves an open issue, please link to it here. For example "Fixes #12345". -->
 <!-- If your change requires a documentation PR, please link it appropriately. -->
 
 ### :memo: Checklist
 
-<!-- Put an `x` in all the boxes that apply. It should be `[x]` not `[x ]`. -->
+<!-- Put an `x` in all the boxes that apply. -->
+<!-- If your change requires a documentation PR, please link it appropriately -->
+<!-- If you're unsure about any of these, don't hesitate to ask. We're here to help! -->
+<!-- Feel free to remove irrelevant items. -->
 
 - [ ] The title is concise, informative, and self-explanatory.
 - [ ] The description explains in detail what this PR is about.