docs: document 15-day PR activity window for new repositories

When a repository is first added to Codacy, only pull requests with
activity in the previous 15 days are automatically analyzed. Added a
note to the managing-repositories page to inform users about this
limitation and how to analyze older PRs via manual reanalysis.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

Author: 2 people

docs/organizations/managing-repositories.md

@@ -48,6 +48,9 @@ To add new repositories to Codacy:
 
 Although Codacy immediately starts analyzing newly added repositories, they display empty metrics until the first analysis returns results.
 
+!!! note
+    When adding a repository, Codacy automatically analyzes pull requests that had activity in the last 15 days. To analyze older pull requests, you can [trigger a reanalysis manually](../faq/repositories/how-do-i-reanalyze-my-repository.md).
+
 ![Waiting for first analysis results](images/repositories-analyzing.png)
 
 ## Following or unfollowing a repository {: id="follow-unfollow"}