add review comment to sb files

[oleksandr-didyk]

Context

Contributes to dotnet/source-build#3435

Adds comments to source-build files asking for the inclusion of the source-build team in PRs that alter SourceBuild* files. Non-reviewed changes could potentially cause issues down the line, be it in the downstream repos or the product build (as has happened in the past, see dotnet/source-build#3435 (comment))

Changes Made

• added comments to source-build files asking for the inclusion of the source-build team in PRs that alter SourceBuild* file.

Testing

Notes

[ladipro]

Curious if we shouldn't add the CODEOWNERS file to enforce such rules.

[oleksandr-didyk]

Curious if we shouldn't add the CODEOWNERS file to enforce such rules.

From past experience CODEOWNERS is a useful tool, but if you are tagging a team alias it will need to have write access to the repo for the entry to work.

Speaking of write access - I don't have it for msbuild so I cannot merge this PR myself. Would be great if someone from the maintainers could merge it. Thanks!