fixup! Update the contributing guide with our new git-cliff setup

CONTRIBUTING.md

@@ -30,18 +30,31 @@ integration tests that need a running synapse instance. These tests reside in
 synapse for testing purposes.
 
 
+## Pull requests
+
+Ideally, a PR should have a *proper title*, with *atomic logical commits*, and
+each commit should have a *good commit message*.
+
+A *proper PR title* would be a one-liner summary of the changes in the PR,
+following the same guidelines of a good commit message, including the
+area/feature prefix. Something like `FFI: Allow logs files to be pruned.` would
+be a good PR title.
+
+(An additional bad example of a bad PR title would be `mynickname/branch name`,
+that is, just the branch name.)
+
 # Writing changelog entries
 
 We aim to maintain clear and informative changelogs that accurately reflect the
 changes in our project. This guide will help you write useful changelog entries
 using git-cliff, which fetches changelog entries from commit messages.
 
-## Commit Message Format
+## Commit message format
 
 Commit messages should be formatted as Conventional Commits. In addition, some
 git trailers are supported and have special meaning (see below).
 
-### Conventional Commits
+### Conventional commits
 
 Conventional Commits are structured as follows:
 
@@ -61,7 +74,7 @@ The type of changes which will be included in changelogs is one of the following
 The scope is optional and can specify the area of the codebase affected (e.g.,
 olm, cipher).
 
-### Changelog Trailer
+### Changelog trailer
 
 In addition to the Conventional Commit format, you can use the `Changelog` git
 trailer to specify the changelog message explicitly. When that trailer is
@@ -70,7 +83,7 @@ leading line. The `Breaking-Change` git trailer can be used in a similar manner
 if the changelog entry should be marked as a breaking change.
 
 
-#### Example Commit Message
+#### Example commit message
 
 ```
 feat: Add a method to encode Ed25519 public keys to Base64