added check for PRs (#13)

We need to be able to verify that the site builds before merging

.github/workflows/check.yml

@@ -0,0 +1,20 @@
+name: PR Check
+
+on:
+  pull_request:
+
+permissions:
+  contents: read
+
+jobs:
+  build-site:
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v4
+      - name: Install node
+        uses: actions/setup-node@v4
+        with:
+          node-version: 20
+      - run: npm ci
+      - run: npm run build