- external links use markdown's []() format,
- local files are formated with backquotes,
- duplicated new lines were removed,
- unnecesary single spaces were removed,
- broken links and local paths were updated.
doc/HACKING/GettingStarted.md says "you might like reading doc/HACKING",
which the reader obviously is already doing. Instead point to the "torguts"
documents that are mentioned a few lines below too.