New guidelines for contribution. (#3045)

* Adding replication and verification step sections and clean up formatting.

* Adding new guidelines for PRs to the CONTRIBUTING docs.

.github/PULL_REQUEST_TEMPLATE.md

@@ -1,5 +1,25 @@
-Fixes # .
+Fixes # 
+--------
 
 Changes proposed:
+---------
+(What are you proposing we change?)
+
 -
 -
+
+Steps to replicate the issue:
+----------
+(If this PR is not fixing a defect/bug, you can remove this section.)
+
+1. 
+2. 
+
+Steps to verify the solution:
+-----------
+(How does someone verify that this does what you think does?)
+
+1.
+2. 
+
+

docs/CONTRIBUTING.md

@@ -35,3 +35,10 @@ To execute the same "release" testing that is performed during CI execution, run
 ## PHPUnit
 
 See [the PHPUnit section in the automated testing docs](testing.md#PHPUnit)
+
+# Submitting Pull Requests
+
+Changes should be submitted as Github Pull Requests to the project repository. To help with review, pull requests are expected to adhere to two main guidelines:
+
+1. PRs should be atomic and targeted at a single issue rather than broad-scope.
+2. PRs are expected to follow the template defined by the project in `.github/ISSUE_TEMPLATE.md`