build: move font generation to the main repo (#2837)

* build: move font generation to the main repo

* Update fonts

* chore: remove submodules

* Update paths

* Update fonts.yml

Co-authored-by: Kevin Barabash <kevinb@khanacademy.org>

dockers/fonts/README.md

@@ -0,0 +1,31 @@
+### How to generate KaTeX fonts and metrics
+
+Originally based on MathJax font generation
+
+#### Fonts
+
+The `buildFonts.sh` script should do everything automatically,
+as long as Docker is installed.
+
+If you want to try out a change
+to [the katex-fonts repository](https://github.com/KaTeX/katex-fonts),
+create a local clone (or download and unpack the ZIP file)
+and specify the path to this directory as an argument to `buildFonts.sh`.
+You can also specify a local or remote tarball,
+e.g. a GitHub download of your own personal feature branch.
+
+The script `buildFonts.sh` automatically creates Docker images
+from the supplied `Dockerfile`.
+It uses the hash of the file to tag the image, so a change to the file
+will result in the creation of a new image.
+If you want to see all created images, run `docker images katex/fonts`.
+To remove all generated images, you can run
+`docker rmi $(docker images --format '{{.Repository}}:{{.Tag}}' katex/fonts)`.
+
+#### Metrics
+
+The script `buildMetrics.sh` generates [metrics](../../src/fontMetricsData.js)
+(dimensions of each character) for the generated fonts.
+See [detailed requirements for running this script](../../src/metrics/).
+
+If there is a problem, file a bug report.