Add a build workflow to test PRs

We will expand this to build/test other things in the future.

.github/workflows/build.yml

@@ -0,0 +1,26 @@
+name: Build and Test
+
+on:
+  pull_request:
+  push:
+    branches:
+      - main
+
+jobs:
+  build:
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v3
+
+      - name: Setup Rust cache
+        uses: Swatinem/rust-cache@v2
+
+      - name: Install mdbook
+        run: cargo install mdbook
+
+      - name: Install mdbook-svgbob
+        run: cargo install mdbook-svgbob
+
+      - name: Test code snippets
+        run: mdbook test