[doc] TOOLS-623 readme copyedit.
- Removed mention of "usage" to remove confusion.
- Prose repo name.
- Add “License" section.
- rm Repository/"Code Layout" section.
- Updated "repo is part of" template.
- Sub-headings markdown.
[doc] TOOLS-623 sdc-heartbeater-agent readme copyedit.
- Better overview.
- Fix line length.