### Description
Improved the `SELF_HOSTING.md` documentation by adding clear
instructions for whitelisting domains in Firebase Authentication.
#### Changes:
- Explained the purpose of Firebase's authorized domains
- Provided a step-by-step guide on how to whitelist your domain(s)
---
### Checks
- [x] Check if any open issues are related to this PR; if so, be sure to
tag them below.
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---
### Issue Reference
Closes [#6809](https://github.com/monkeytypegame/monkeytype/issues/6809)
### Description
Improved grammar, structure, and tone of the `docs/self_hosting.md` file
for better clarity and consistency. Changes include fixing typos,
rewording vague instructions, improving formatting, and aligning with
the overall documentation tone.
### Checks
- [x] Make sure the PR title follows the Conventional Commits standard.
(https://www.conventionalcommits.org for more info)
- [x] Make sure to include your GitHub username prefixed with @ inside
parentheses at the end of the PR title.
### Other notes
This PR does not add any quotes, languages, themes, or layouts.
---
Closes # (none)
- fixes /configure endpoint not working in docker image because of the
missing `private` directory
- adds `export configuration` button to api server configuration
