Fixing - to have single source of truth for documentation

[surapuramakhil]

Have noticed same docs information exists at multiple places (It's same as Software Engineering DRY principle)

this one seems to be updated frequently
https://github.com/apache/superset/blob/master/CONTRIBUTING.md

but official docs aren't (outdated)
https://github.com/apache/superset/tree/master/docs/docs

Can we map official docs to sections of this in https://github.com/apache/superset/blob/master/CONTRIBUTING.md wherever it's repeated?

[surapuramakhil]

PR related to this i guess.
#28220