Revert "[CI] Remove docs build"

This reverts commit bdb72b2e2a.

.gitea/workflows/build-docs.yml

@@ -0,0 +1,29 @@
+name: Build docs
+on:
+  push
+  # push:
+  #   paths:
+  #     - 'docs/**'
+jobs:
+  build_docs:
+    runs_on: ubuntu-latest
+    steps:
+      - name: Set up Git repository
+        uses: actions/checkout@v6
+      - name: Sign into gitea registry
+        uses: https://github.com/docker/login-action@v3
+        with:
+          username: ${{ vars.REGISTRY_USER_USERNAME }}
+          password: ${{ secrets.REGISTRY_USER_PASSWORD }}
+          registry: ${{ vars.REGISTRY_BASE_URL }}
+      - name: Run build
+        uses: actions/latex@main
+        with:
+          workdir: docs
+      - name: Upload compiled docs
+        uses: actions/git-auto-commit-action@v7
+        with:
+          commit_message: "[skip ci] Build docs on push"
+          file_pattern: '*.tex'
+          commit_user_name: LaTeX compiler [bot]
+          commit_user_email: actions@janishutz.com