docs: add build step for autodoc

Add build step to generate autodocs and add github workflow for
publishing

.github/workflows/docs.yml

@@ -0,0 +1,38 @@
+name: docs
+
+on:
+  push:
+    branches: ["main"]
+  workflow_dispatch:
+
+permissions:
+  contents: read
+  pages: write
+  id-token: write
+
+concurrency:
+  group: "pages"
+  cancel-in-progress: true
+
+jobs:
+  deploy:
+    environment:
+      name: github-pages
+      url: ${{ steps.deployment.outputs.page_url }}
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v3
+      - name: Setup Pages
+        uses: actions/configure-pages@v2
+      - uses: goto-bus-stop/setup-zig@v2
+        with:
+          version: master
+      - run: zig build docs
+      - name: Upload artifact
+        uses: actions/upload-pages-artifact@v1
+        with:
+          path: "zig-out/docs"
+      - name: Deploy to GitHub Pages
+        id: deployment
+        uses: actions/deploy-pages@v1

build.zig

@@ -60,4 +60,14 @@ pub fn build(b: *std.Build) void {
 
     lints_step.dependOn(&lints.step);
     b.default_step.dependOn(lints_step);
+
+    // Docs
+    const vaxis_docs = tests;
+    const build_docs = b.addInstallDirectory(.{
+        .source_dir = vaxis_docs.getEmittedDocs(),
+        .install_dir = .prefix,
+        .install_subdir = "docs",
+    });
+    const build_docs_step = b.step("docs", "Build the vaxis library docs");
+    build_docs_step.dependOn(&build_docs.step);
 }