Revisions for review - Training Suite

Hiya EOWG folks,

I did some updating of the training resource suite. Thanks to Vivienne and team for investing quite a bit of effort to try to sort through all of the updates needed!

Note that I did not revise language*, change substantive content, or make other updates that need more time and EOWG consideration. [*with a few exceptions to match our Style guide, etc.] Certainly this resource could benefit from much more effort to update and revise it.

However, the goal for now was just to get new links added and resource names updated so it's not egregiously out-of-date for the new site. (It's likely that I missed some; suggestions welcome.)

If you add any GitHub issues or pull requests that you think they need to be addressed urgently, please:
 *select the Label "before May launch"*
All other comments will likely be considered for later revision.

Main changes:
* Added links to tutorials, videos, getting started tips, WCAG-EM
* Updated document names and some descriptions
* Organized and formatted for new design
(Note that some of the new links were added to the Topics page and not also to the other pages, because the other pages link to the Topics page.)

1. Overview
* New: https://w3c.github.io/wai-develop-training/teach-advocate/accessibility-training/
* Old: https://www.w3.org/WAI/training/
* Diff attached
* To comment: https://github.com/w3c/wai-develop-training/issues/new?title=[overview]

2. Topics
* New: https://w3c.github.io/wai-website/teach-advocate/accessibility-training/topics/
* Old: https://www.w3.org/WAI/training/topics
* Diff attached
* To comment: https://github.com/w3c/wai-develop-training/issues/new?title=[topics]

3. Presentation outline examples
* New: https://w3c.github.io/wai-website/teach-advocate/accessibility-training/presentation-outlines/
* Old: https://www.w3.org/WAI/training/presentation-outlines
* Diff attached
* To comment: https://github.com/w3c/wai-develop-training/issues/new?title=[presentations]

4. Workshop
* New: https://w3c.github.io/wai-website/teach-advocate/accessibility-training/workshop-outline/
* Old: https://www.w3.org/WAI/training/workshop-outlines
* Diff attached
* To comment: https://github.com/w3c/wai-develop-training/issues/new?title=[workshop]

Best,
~Shawn