scripts: GenWorld doc tweaks
NotSoFlat:
 **   - multiple ground configs depending of height
 **   - cactus and weeds generation on sand
 **   - fn and dotsz settings to tweak the look of the environment
 **   - richer set of presets
NotSoFlat: doc update
Merge branch 'NotSoFlat-dev' into dev

* NotSoFlat-dev:
  NotSoFlat: doc update
  NotSoFlat:
  **   - multiple ground configs depending of height
  **   - cactus and weeds generation on sand
  **   - fn and dotsz settings to tweak the look of the environment
  **   - richer set of presets
  scripts: GenWorld doc tweaks