Removed reference to Cactus from documentation

Issue: SPR-11280
Merge pull request #435 from snicoll/SPR-11280

* SPR-11280:
  Removed reference to Cactus from documentation
Improve the "contributing documentation" readme

Update the "contributing documentation" readme to include the correct
gradle goal and provide a troubleshooting section.
Hard-wrap CONTRIBUTING-DOCUMENTATION at 90 chars
Merge pull request #434 from snicoll/ascidoc-liveupdate

* ascidoc-liveupdate:
  Hard-wrap CONTRIBUTING-DOCUMENTATION at 90 chars
  Improve the "contributing documentation" readme
Fix various documentation issues

- Remove formatting that interferes with code highlighting
- Fix some XML syntax issues
- Added missing punctuation
Merge pull request #429 from VasylTretiakov/master

* pull429:
  Fix various documentation issues