Add new ci file

.github/workflows/ci-docs.yml

@@ -0,0 +1,25 @@
+name: Check Website
+on:
+  pull_request:
+    branches:
+      - "current-docs"
+      - "master"
+jobs:
+  check-website:
+    runs-on: ubuntu-20.04
+    steps:
+      - uses: actions/checkout@v2.4.0
+        with:
+          fetch-depth: 0
+      - name: Set current version
+        run:  echo "DOCSPELL_VERSION=$(cat version.sbt | grep version | cut -d= -f2 | xargs)" >> $GITHUB_ENV
+      - uses: jorelali/setup-elm@v3
+        with:
+          elm-version: 0.19.1
+      - uses: cachix/install-nix-action@v16
+        with:
+          nix_path: nixpkgs=channel:nixos-21.11
+      - name: Print nixpkgs version
+        run: nix-instantiate --eval -E '(import <nixpkgs> {}).lib.version'
+      - name: Build website (${{ env.DOCSPELL_VERSION }})
+        run: nix-shell website/shell.nix --run "sbt make-website"