Update related projects

Author: cytopia

README.md

@@ -71,9 +71,11 @@ updates:
 | Name                         | Description |
 |------------------------------|-------------|
 | [docker-tag-action]          | Determines Docker tags based on git branch, commit or git tag |
+| [git-ref-matrix-action]      | Create stringified JSON list of git refs to be used as a build matrix |
 | [shell-command-retry-action] | Retries shell commands to avoid failing pipelines due to network issues |
 
 [docker-tag-action]: https://github.com/cytopia/docker-tag-action
+[git-ref-matrix-action]: https://github.com/cytopia/git-ref-matrix-action
 [shell-command-retry-action]: https://github.com/cytopia/shell-command-retry-action