[chore] Vendor mkdocs fonts; update docs dependencies (#2789)

* [chore] Update docs dependencies

* update rtd deps

* aaaa

* why can't you just be normal!

* vendor social plugin fonts

CONTRIBUTING.md

@@ -110,7 +110,13 @@ When adding a new page, you need to include it in the [`mkdocs.yml`](mkdocs.yml)
 
 If you don't use Conda, you can read the `docs/environment.yml` to see which dependencies are required and `pip install` them manually. It's advisable to do this in a virtual environment, which you can create with something like `python3 -m venv /path-to/store-the-venv`. You can then call `/path-to/store-the-venv/bin/pip`, `/path-to/store-the-venv/bin/mkdocs` etc.
 
-In order to upgrade dependencies, use `conda update --update-all` in the activated environment. You can then update the `environment.yml` with `conda env export --from-history -f ./docs/environment.yml`, though you'll need to fix the `channels`. Beware that `conda env export` will also drop the `pip` dependencies, so make sure to add those back.
+In order to upgrade dependencies, use `conda update --update-all` in the activated environment. You can then update the `environment.yml` with:
+
+```sh
+conda env export -n gotosocial-docs --from-history --override-channels -c conda-forge -c nodefaults -f ./docs/environment.yml
+```
+
+Beware that `conda env export` will add a `prefix` entry to the environment.yml file, and drop the `pip` dependencies, so make sure to remove the prefix and add the `pip` dependencies back in.
 
 ## Development