Contributing.MD was not updated for repository rearrangement in relation to the index.d.ts link

[brantgurga]

The Contributing.md file was not updated and refers to a single index.d.ts file that contains the documentation. Such files got moved around at some point so that link is no longer correct and overall concept may no longer be right.

[google-oss-bot]

I couldn't figure out how to label this issue, so I've labeled it for a human to triage. Hang tight.

[brantgurga]

The move/removal of index.d.ts seemed to come in cdada6c for context

[hsubox76]

We need to update the Updating Documentation section and keep the current section as "how to update compat docs" and move it lower, and add a new, top section on "how to update modular docs". The "how to find what text to update" part is not going to be simple but we should explain the general idea of it and I guess encourage people to search and do their best, and then the generation is just yarn docgen devsite.