docs: Fix a few typos

[timgates42]

There are small typos in:

• docs/how-to/customize_look_and_feel.rst
• docs/how-to/rewriting_entry_url.rst
• docs/index.rst
• docs/notes/faq.rst
• zinnia/markups.py
• zinnia/models/entry.py
• zinnia/models_bases/entry.py
• zinnia/static/zinnia/admin/dashboard/js/masonry.pkgd.js
• zinnia/views/mixins/entry_protection.py

Fixes:

• Should read different rather than differents.
• Should read upon rather than uppon.
• Should read reimplementing rather than reimplemting.
• Should read optionally rather than optionnally.
• Should read multilingual rather than multiplingual.
• Should read initialized rather than initalized.
• Should read inheritance rather than inheritence.
• Should read implementing rather than implemeting.
• Should read implementation rather than implemention.

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