ci: 👷 add build-website action (#24)

# Description

Copied from `wp1-ros`

This PR needs a quick review.

---------

Co-authored-by: Luke W. Johnston <lwjohnst@gmail.com>

Author: signekb

.github/workflows/build-website.yml

@@ -0,0 +1,21 @@
+name: Build website
+
+on:
+  push:
+    branches:
+      - main
+
+# To force read only on all permissions at workflow level.
+permissions: read-all
+
+jobs:
+  build-website:
+    uses: seedcase-project/.github/.github/workflows/reusable-build-docs.yml@main
+    # Only need these for this job.
+    permissions:
+      contents: write
+      pages: write
+    with:
+      hosting-provider: gh-pages
+    secrets:
+      github-token: ${{ secrets.GITHUB_TOKEN }}