Repo contribution rules update

TTS Leadership has asked us of the data.gov (and other teams) to add this statement to "all" of our repos.
I'm not sure what "all" means - is this just the data.gov repo? or truely each one.. Leadership said "if the repo or external page does not reference the TTS Code of Conduct, then not edits need to be made" - This makes me think we should also search our static webpages for "TTS Code of Conduct"

**Statement: By contributing to this repository, you agree to adhere to the [GSA Social Media Policy](https://www.gsa.gov/directives-library/gsa-social-media-policy-2). We expect all contributors, both internal and external, to engage respectfully and professionally in all project-related public communications.**

This would replace some statement about TTS Code of Conduct (which no longer exists).

Please keep records in this ticket about what repo was updated and when, as Sue needs to report this to leadership.

Done when:

- All repos that mention TTS Code of Conduct instead have the statement above
- All static webpages that mention TTS Code of Conduct have been A) fixed to reference TTS Social Media Policy --OR-- B) a new ticket has been written to track the update of any needed changes on the static webpage.

Start by identifying repositories and static webpages that mention the TTS Code of Conduct, then record the repository updates and dates in this ticket. Replace applicable repository references with the supplied GSA Social Media Policy statement, or create a follow-up ticket for static webpage changes. Done when all identified references are updated or tracked.

Written by the indexing model from the issue text.