Suggestion: Community contributor, SIG info, reviewers split

[sptramer]

During review of https://github.com/o3de/community/pull/158, it became clear that information about community, SIGs, and available reviewer/maintainer roles is duplicated or split in a hard-to-discover way across multiple files. This issue is for awareness of the problem to produce a full RFC if needed, or at least discussion within the project.

As a starting point, I would suggest the following be how the information is maintained and organized:

• README.md - Should not just be an index of the SIGs/repos - should be a short summary of the project, who we are, etc.
• CONTRIBUTING.md - The current community-membership.md page should be merged into CONTRIBUTING.md, excepting the role descriptions.
• ROLES.md - An expanded description of community roles (currently maintained in the docs affected by #158) including chairperson, TSC/TAC roles and how they are staffed, as well as links to any SIG-specific roles (such as sig-docs-community requiring a "Website reviewer" role)

[lmbr-pip]

We just pushed an update to the README which I think gives more of an overview view of the project/repro.

Agree that the how to contribute sections of community-membership.md should be merged with CONTRIBUTING.md

Would not agree with renaming community-membership.md to ROLES.md but instead have that be a list of roles ie contributor, maintainer, reviewer, chair and co-chair and TSC membership. This is because this page is more deeply linked than you would expect and we can use informational links to highlight the content here.