* update quickstart and remove os import
* simplify theme use
* list sphinx_rtd_theme as extension
Our docs builds failed last night, presumably because #9754 updated `sphinx_rtd_theme` which changed some unknown thing.
Looking into it, our usage of this project was very unconventional. Following the code comment I deleted in this PR to https://docs.readthedocs.io/en/stable/faq.html#i-want-to-use-the-read-the-docs-theme-locally, simple instructions are given to put the following in your `conf.py` file:
```
extensions = [
...
'sphinx_rtd_theme',
]
html_theme = "sphinx_rtd_theme"
```
I did this instead of the more complicated logic we were using and all builds passed locally. I also triggered a build on readthedocs with these changes which also passed.
Currently if you go to https://certbot.eff.org/docs/api/certbot.crypto_util.html, there is a todo comment displayed at the top of the page. These todos were written for developers, not users, so I do not think they should be shown from our documentation.
This PR makes the quick and easy fix of configuring Sphinx not to show these todo items. I created #7752 to track removing all of these todos from our docstrings and disabling the Sphinx todo extension.
* Set todo_include_todos=False in sphinx-quickstart
* Remove todos from existing docs.
It looks like we're currently documenting functions that are marked private (prefixed with an underscore) such as https://certbot.eff.org/docs/api/certbot.crypto_util.html#certbot.crypto_util._load_cert_or_req. I do not think we should do this because the functionality is private, should not be used, and including it in our docs just adds visual noise.
This PR stops us from documenting private code and fixes up `tools/sphinx-quickstart.sh` so we don't document it in future modules.
* Do not document private code.
* Don't document private members in the future.
