Complete the remaining items in the Community profile

[myii]

I.e. https://github.com/saltstack-formulas/template-formula/community.

Also work out if they should be converted to .rst and added under docs/ instead, so that they can appear in RTD as well.

[myii]

Likewise, this has appeared recently: https://github.com/saltstack-formulas/template-formula/security/advisories.

[myii]

This has been effectively taken care of org-wide by the .github repo.