Add workflow for publishing website

Builds an publishes the website on each push to `current-docs` branch.

.github/workflows/website.yml

@@ -0,0 +1,26 @@
+name: Publish Website
+on:
+  push:
+    branches:
+      - "current-docs"
+jobs:
+  publish-website:
+    runs-on: ubuntu-20.04
+    steps:
+      - uses: actions/checkout@v2.3.4
+        with:
+          fetch-depth: 0
+      - name: Set current version
+        run:  echo "DOCSPELL_VERSION=$(cat version.sbt | grep version | cut -d= -f2 | xargs)" >> $GITHUB_ENV
+      - uses: jorelali/setup-elm@v3
+        with:
+          elm-version: 0.19.1
+      - uses: cachix/install-nix-action@v13
+        with:
+          nix_path: nixpkgs=channel:nixos-20.09
+      - name: Print nixpkgs version
+        run: nix-instantiate --eval -E '(import <nixpkgs> {}).lib.version'
+      - name: Build website (${{ env.DOCSPELL_VERSION }})
+        run: nix-shell website/shell.nix --run "sbt make-website"
+      - name: Publish website (${{ env.DOCSPELL_VERSION }})
+        run: sbt publish-website

build.sbt

@@ -787,3 +787,5 @@ addCommandAlias(
   "scalafmtSbtCheck; scalafmtCheckAll; Compile/scalafix --check; Test/scalafix --check"
 )
 addCommandAlias("fix", "Compile/scalafix; Test/scalafix; scalafmtSbt; scalafmtAll")
+addCommandAlias("make-website", ";website/clean ;website/zolaBuild ;website/zolaCheck")
+addCommandAlias("publish-website", "website/publishToGitHubPages")