docs: Fix a few typos

[timgates42]

There are small typos in:

• examples/spinner_ext_example.py
• examples/treeview_filter_example.py

Fixes:

• Should read positioned rather than positionned.
• Should read milliseconds rather than miliseconds.

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

[sebp]

Thanks a lot!