[chore] Add 'RPC' and 'Service and Deployment' sigs

[joaopgrassi]

Add in the recently created SIGs/Project to our metadata file. The GH team user is missing still but once those are created I will update again.

Merge requirement checklist

• CONTRIBUTING.md guidelines followed.
• Change log entry added, according to the guidelines in When to add a changelog entry.
  • If your PR does not need a change log, start the PR title with [chore]
• Links to the prototypes or existing instrumentations (when adding or changing conventions)