feat: enforce single commit requirement

Describe why a single commit is very important.

Signed-off-by: Serge Logvinov <[email protected]>

Author: sergelogvinov

.conform.yaml

@@ -12,7 +12,7 @@ policies:
       gpg: false
       spellcheck:
         locale: US
-      maximumOfOneCommit: false
+      maximumOfOneCommit: true
       conventional:
         types:
           - build

CONTRIBUTING.md

@@ -1,5 +1,15 @@
 # Contributing
 
+## Pull Requests
+
+All PRs require a single commit.
+
+Having one commit in a Pull Request is very important for several reasons:
+* A single commit per PR keeps the git history clean and readable.
+  It helps reviewers and future developers understand the change as one atomic unit of work, instead of sifting through many intermediate or redundant commits.
+* One commit is easier to cherry-pick into another branch or to track in changelogs.
+* Squashing into one meaningful commit ensures the final PR only contains what matters.
+
 ## Developer Certificate of Origin
 
 All commits require a [DCO](https://developercertificate.org/) sign-off.