Added readme_check_guideline.md along with the check_guideline.py
to explain the usage of this and to show how it should be used.
Signed-off-by: Iulia Moldovan <iulia.moldovan@analog.com>
* Updated action to run only in PRs on master branch, on library/ and
projects/ paths
* Edited the text for the printed warnings
* Updated the version for the checkout action from v2 to v3
Signed-off-by: Iulia Moldovan <iulia.moldovan@analog.com>