Bridge Developer Docs

[VenelinMartinov]

Adds sphinx-based developer documentation to the bridge. Similar to https://github.com/pulumi/pulumi/pull/16953

Can be previewed here: https://pulumi-terraform-bridge.readthedocs.io/en/latest/docs/README.html

[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 62.84%. Comparing base (4b48eb8) to head (2a6afc1). Report is 7 commits behind head on master.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## master #2623 +/- ## ========================================== + Coverage 62.83% 62.84% +0.01% ========================================== Files 390 390 Lines 51954 51967 +13 ========================================== + Hits 32644 32659 +15 + Misses 17506 17503 -3 - Partials 1804 1805 +1 ```

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[VenelinMartinov]

The developer docs site rebuilds on each commit, currently on this branch but I'll redirect it to master after merging. The credentials are in the password store.

~This can indeed be a section under the main docs but we need some additional work there.~ There is now a link in the main docs to this one, thanks @lunaris

Well spotted on the different syntax for diagrams, ~quite unfortunate though = (~ EDIT: Apparently that's configurable, I've made it compatible with the Github syntax now.

[VenelinMartinov]

We've now added a link to the Bridge docs from the main docs and one from the Bridge docs to the main docs. I've also expanded on the home page to link to a few useful topics.

[pulumi-bot]

This PR has been shipped in release v3.96.0.