Add a SOP of how to submit projects

[virtuslab]

Add a SOP of how to submit projects

[WojciechMazur]

In case of published libraries there is no need to do that, they're automatically added based on data from ScalaDex. In case of open-source non-library or not yet published projects they can be added to
https://github.com/VirtusLab/community-build3/blob/master/coordinator/configs/custom-projects.txt

Some of the projects might be filtered-out if they're non compliant, eg. they have build issues, require special environment or don't compile with any recent version of Scala for long time (are unmaintained). Such projects are enlisted here:
https://github.com/VirtusLab/community-build3/blob/master/coordinator/configs/filtered-projects.txt

Each project might define it's config (HOCON) describing how should we handle it, eg. which JDK version to use, to exclude some legacy modules, add some sbt options, or disable compilation/running tests if they're buggy/flaky. It can be defined in projects top-level file or in our internal config maintained here:
https://github.com/VirtusLab/community-build3/blob/master/coordinator/configs/projects-config.conf

Based on all of these we create a build plan enlisting projects which we should run, and their final config used when compiling them. We do this each automatically every Friday few hours before running the weekly build.

I'll try to write it down to make it more clear. Until this time there are 2 posts about Open CB and how it works:

• https://virtuslab.com/blog/prevent-scala3-compiler-regressions-community-build/
• https://virtuslab.com/blog/how-to-be-a-part-of-scalas-open-community-build/

[He-Pin]

Thanks for the detailed declaration.

[WojciechMazur]

Updated the ReadMe to contain all the required info.