Overhaul of ServiceX Docs for 3.0 release

[BenGalewsky]

• Major PR for the documentation of 3.0 client library
• This resolves #446

[codecov[bot]]

Codecov Report

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

Project coverage is 82.92%. Comparing base (2dfb069) to head (2d248b1). Report is 53 commits behind head on 3.0_develop.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## 3.0_develop #444 +/- ## =============================================== + Coverage 82.02% 82.92% +0.90% =============================================== Files 26 26 Lines 1363 1429 +66 =============================================== + Hits 1118 1185 +67 + Misses 245 244 -1 ``` | [Flag](https://app.codecov.io/gh/ssl-hep/ServiceX_frontend/pull/444/flags?src=pr&el=flags&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=ssl-hep) | Coverage Δ | | |---|---|---| | [unittests](https://app.codecov.io/gh/ssl-hep/ServiceX_frontend/pull/444/flags?src=pr&el=flag&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=ssl-hep) | `82.92% <100.00%> (+0.90%)` | :arrow_up: | Flags with carried forward coverage won't be shown. [Click here](https://docs.codecov.io/docs/carryforward-flags?utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=ssl-hep#carryforward-flags-in-the-pull-request-comment) to find out more.

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[ketan96-m]

As a final step to merge to 3.0_develop, removing the doc_week entry from the docs.yml file.

[matthewfeickert]

• This resolves docs: Add link back to GitHub repository from the documentation #446

Just for future reference (doesn't matter here), putting text in front of Resolves #XXX breaks the operations. So it needs to literally be just

* Resolves #446