docs: Fix a few typos

[timgates42]

There are small typos in:

• docs/api.rst
• docs/usage.rst
• examples/collection.py

Fixes:

• Should read possibilities rather than possibilites.
• Should read entities rather than entitities.
• Should read collection rather than collction.
• Should read automatically rather than automaticall.

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

[alastair]

Thanks!