Indicate limitation of the solution in the documentation

[alex-ilgayev]

We have several limitations in our solution that we should indicate in the documentation:

• when we search for dependent action in uses: string, we search for the repository in the default branch, and not in the indicated branch. For example: - uses: myorg/myaction@dev. We won't be looking in dev branch, but in the default branch. Example: take care for references when downloading dependenct actions #38
• Sometimes we won't find the referenced action if it doesn't exist in the repository and was checked out in a previous step from a different repository. Example: take care for action references that are submodules #39
• Sometimes we won't find the action when Dockerfile was used to build the action, and not action.yml.
• We aren't modeling the entire workflow file, and we miss much information - like permissions tags for jobs/steps, and more.