Copyedit on Private Advanced Git Training at JavaZone

The last commit on this file mentioned it being a first draft, wasn't sure if that meant you had the next draft on hand, hopefully you don't, and so here this is:

- Added "at JavaZone" to help differentiate in listing
- Signed Tags, Bisect could do with a step up to H3
- Forgoing bare URLs for linked words, for web aesthetic
- Bullets in Audience Requirements feels like H2 time
- Last Required bullet point may not be required