docs: improve updating pre-commit documentation (#1361)

- there was a inconsistence between the inline and rej default. as it's inline I changed the value in the corrected section
- as users won't need the 2 options at once, I split the 2 hooks.
- specified that both repos can be used at once

Co-authored-by: Sigurd Spieckermann <2206639+sisp@users.noreply.github.com>

docs/updating.md

@@ -61,7 +61,21 @@ setting you use.
 
 ## Preventing Commit of Merge Conflicts
 
-If you use `--conflict rej` (the default):
+If you use `--conflict inline` (the default) then you need to check for conflicts
+markers in your files:
+
+```yaml title=".pre-commit-config.yaml"
+repos:
+    - repo: https://github.com/pre-commit/pre-commit-hooks
+      rev: v4.3.0
+      hooks:
+          # Prevent committing inline conflict markers
+          - id: check-merge-conflict
+            args: [--assume-in-merge]
+```
+
+If you use `--conflict rej` then you need to review and remove all generated `.rej`
+files:
 
 ```yaml title=".pre-commit-config.yaml"
 repos:
@@ -70,17 +84,19 @@ repos:
           # Prevent committing .rej files
           - id: forbidden-files
             name: forbidden files
-            entry: found Copier update rejection files; review them and remove them
+            description:
+                found Copier update rejection files; review and remove them before
+                merging.
             language: fail
             files: "\\.rej$"
-    - repo: https://github.com/pre-commit/pre-commit-hooks
-      rev: v4.3.0
-      hooks:
-          # Prevent committing inline conflict markers
-          - id: check-merge-conflict
-            args: [--assume-in-merge]
 ```
 
+!!! note
+
+    For projects that use both `rej` and `inline` depending on each user's preference,
+    you can add both hooks to your `pre-commit-config.yaml` file, making sure that no
+    unresolved merge conflicts are committed.
+
 ## Never change the answers file manually
 
 !!! important