docs: Fix a few typos

[timgates42]

There are small typos in:

• blitzdb/backends/file/backend.py
• blitzdb/backends/file/index.py
• blitzdb/backends/sql/backend.py
• docs/source/backends/index.rst
• docs/source/tutorials/basics.rst
• tests/test_sorting.py

Fixes:

• Should read comparison rather than comparision.
• Should read sufficient rather than sufficent.
• Should read separately rather than seperately.
• Should read include rather than inlcude.
• Should read existent rather than existant.
• Should read autocommit rather than autocomit.
• Should read ascending rather than asending.
• Should read ambiguous rather than ambigous.

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