Proposing a PR to fix a few small typos

[timgates42]

Issue Type

[x] Bug (Typo)

Steps to Replicate and Expected Behaviour

• Examine procedural_city_generation/building_generation/building_generation_params.py, procedural_city_generation/polygons/polygons_params.py, procedural_city_generation/roadmap/roadmap_params.py, procedural_city_generation/visualization/visualization_params.py and observe recommmended, however expect to see recommended.
• Examine doc/index.rst and observe possibilty, however expect to see possibility.
• Examine UI.py and observe paremeter, however expect to see parameter.
• Examine procedural_city_generation/additional_stuff/clean_tools.py and observe occurence, however expect to see occurrence.
• Examine procedural_city_generation/additional_stuff/Singleton.py and observe instanciated, however expect to see instantiated.
• Examine doc/index.rst and observe illustation, however expect to see illustration.
• Examine procedural_city_generation/visualization/blenderize.py and observe direcotry, however expect to see directory.

Notes

Semi-automated issue generated by
https://github.com/timgates42/meticulous/blob/master/docs/NOTE.md

To avoid wasting CI processing resources a branch with the fix has been
prepared but a pull request has not yet been created. A pull request fixing
the issue can be prepared from the link below, feel free to create it or
request @timgates42 create the PR. Alternatively if the fix is undesired please
close the issue with a small comment about the reasoning.

https://github.com/timgates42/procedural_city_generation/pull/new/bugfix_typos

Thanks.