Mention forks in the README.md limitations

README.md

@@ -153,6 +153,9 @@ with the summary of the code coverage changes.
 - Currently, code coverage profiles are uploaded as GitHub artifacts which automatically expire after 90 days.
   In a repository which receives changes only infrequently, this might lead to issues when trying to compare
   the code coverage of a pull request with the code coverage of the main branch (see fgrosse/go-coverage-report#5).  
+- Support **for forks** is limited since the necessary `GITHUB_TOKEN` permissions don't allow to post comments to the
+  pull request of the base repository (see fgrosse/go-coverage-report#15). If forks are important for you, this action
+  might not be the best solution.
 - Packages with a name that differs from their directory on disk are not supported yet.
 - Requires `actions/upload-artifact` >= **v4** (see this [issue][upload-artifacts-issues]).