chore: add build workflow

.github/workflows/build.yml

@@ -0,0 +1,18 @@
+name: Eleventy Build
+on: [push]
+
+jobs:
+  build_deploy:
+    runs-on: ubuntu-18.04
+    steps:
+      - uses: actions/checkout@master
+      - name: Build
+        uses: TartanLlama/actions-eleventy@master
+				with:
+					install_dependencies: true
+      - name: Deploy
+        uses: peaceiris/actions-gh-pages@v3
+        with:
+          publish_dir: _site
+          publish_branch: gh-pages
+          github_token: ${{ secrets.GITHUB_TOKEN }}

.gitignore

@@ -1,3 +1,2 @@
 _site/
 node_modules/
-package-lock.json