Find all users and get them to migrate off actions-includes

[mithro]

Given this project is mostly abandoned, it would be good to notify any users and get them to migrate onto a better supported solution.

[mithro]

FYI - @kgugala - We should get f4pga / symbiflow off actions-includes now there are better supported solutions from GitHub.

[mithro]

FYI - @umarcor

[awoimbee]

Hi, I just migrated to composite actions. I wanted to say thank you for actions-includes, it was a great tool.

A good way to get people off actions-includes would be to update it to print a warning when run IMO.

[mithro]

@awoimbee - Thanks for that idea, it is a great plan!

@awoimbee - It would be great to see how you converted from actions-includes to composite actions, would you mind linking to the pull request or commits?