finish setup doxygen (#458)

* update and setup doxygen file

* move to docs/html

* Readme - Add link to the documentation

.github/workflows/doxygen-gh-pages.yml

@@ -0,0 +1,18 @@
+name: Doxygen GitHub Pages Deploy Action
+
+on:
+  push:
+    branches:
+      - master
+  workflow_dispatch:
+
+jobs:
+  deploy:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: DenverCoder1/doxygen-github-pages-action@v1.3.0
+        with:
+          github_token: ${{ secrets.GITHUB_TOKEN }}
+          branch: gh-pages
+          folder: docs/html
+          config_file: Doxyfile

.gitignore

@@ -81,3 +81,6 @@ expected/*
 !/sound/**/*custom*/**/*.aiff
 !/assets/**/*custom*.bin
 !/assets/**/*custom*/**/*.bin
+
+# Doxygen
+docs/html/*

README.md

@@ -106,6 +106,11 @@ Some menu textures are compressed using a format called tkmk00. A byte-matching
 	|   └── trophy: ceremony cutscene podium and trophy textures
 	└── tools: build tools
 
+## Documentation
+
+[Doxygen](https://www.doxygen.nl/index.html) is used to generate documentation. To generate the documentation, run `doxygen Doxyfile` from the project root. The documentation will be generated in the `docs/html` folder.
+The documentation is also available online at [https://n64decomp.github.io/mk64/](https://n64decomp.github.io/mk64/).
+
 ## Contributing
 
 Pull requests are welcome. For major changes, please discuss in the Discord.