Update About page of documentation

[kyungeonchoi]

• A table of presentations on the client only (or major topic is client) for users who want to know more about the client
• Response to the issue by @matthewfeickert - https://github.com/ssl-hep/ServiceX_frontend/issues/465

[codecov[bot]]

Codecov Report

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

Project coverage is 87.16%. Comparing base (273ea34) to head (53d10c5).

Additional details and impacted files

```diff @@ Coverage Diff @@ ## master #526 +/- ## ======================================= Coverage 87.16% 87.16% ======================================= Files 27 27 Lines 1675 1675 ======================================= Hits 1460 1460 Misses 215 215 ``` | [Flag](https://app.codecov.io/gh/ssl-hep/ServiceX_frontend/pull/526/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/526/flags?src=pr&el=flag&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=ssl-hep) | `87.16% <ø> (ø)` | | 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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• Flaky Tests Detection - Detect and resolve failed and flaky tests

[matthewfeickert]

Thanks @kyungeonchoi. You can probably also use the Resolves #465 here as I think you'll do a great job of addressing things here.