feat: add a 'last updated' line on all content

[jswongF5]

Reviewers

@alankrit8.

Issue

We want to know when a page was last updated. This help people get an idea how old or new pages are.

The format of last updated can be defined in conf.py file. Example below.

html_last_updated_fmt = '%B %d %Y at %I:%M:%S %p %Z'

And if you want to pin a timezone:

html_last_updated_fmt = '%B %d %Y at %I:%M:%S %p %Z'
git_last_updated_timezone = 'US/Pacific'

extensions = [
    . . .
    'sphinx_last_updated_by_git',
]

Screenshot: