chore: Add github action to build docs (#55)

Add the infrastructure for addressing #5 and #6 in subsequent pull requests.

.github/workflows/docs.yml

@@ -0,0 +1,45 @@
+name: Publish Docs
+
+on:
+  # Runs on pushes targeting the default branch
+  push:
+    branches: ["main"]
+
+# Sets permissions of the GITHUB_TOKEN to allow deployment to GitHub Pages
+permissions:
+  contents: read
+  pages: write
+  id-token: write
+
+# Allow one concurrent deployment
+concurrency:
+  group: "pages"
+  cancel-in-progress: true
+
+jobs:
+  deploy:
+    environment:
+      name: github-pages
+      url: ${{ steps.deployment.outputs.page_url }}
+    runs-on: macos-12
+    steps:
+      - name: Checkout 🛎️
+        uses: actions/checkout@v3
+      - name: Package documentation 🛠
+        run: |
+          export DOCC_JSON_PRETTYPRINT="YES"
+          swift package \
+            --allow-writing-to-directory ./docs \
+            generate-documentation --target WMATAUI \
+            --disable-indexing \
+            --transform-for-static-hosting \
+            --hosting-base-path WMATAUI \
+            --output-path ./docs
+      - name: Upload artifact 📜
+        uses: actions/upload-pages-artifact@v1
+        with:
+          # Upload docs directory
+          path: 'docs'
+      - name: Deploy to GitHub Pages 🐙
+        id: deployment
+        uses: actions/deploy-pages@v1

Package.resolved

@@ -1,5 +1,23 @@
 {
   "pins" : [
+    {
+      "identity" : "swift-docc-plugin",
+      "kind" : "remoteSourceControl",
+      "location" : "https://github.com/apple/swift-docc-plugin",
+      "state" : {
+        "revision" : "26ac5758409154cc448d7ab82389c520fa8a8247",
+        "version" : "1.3.0"
+      }
+    },
+    {
+      "identity" : "swift-docc-symbolkit",
+      "kind" : "remoteSourceControl",
+      "location" : "https://github.com/apple/swift-docc-symbolkit",
+      "state" : {
+        "revision" : "b45d1f2ed151d057b54504d653e0da5552844e34",
+        "version" : "1.0.0"
+      }
+    },
     {
       "identity" : "swift-protobuf",
       "kind" : "remoteSourceControl",

Package.swift

@@ -18,7 +18,8 @@ let package = Package(
     ],
     dependencies: [
         .package(url: "https://github.com/emma-k-alexandra/WMATA.swift", from: "15.1.0"),
-        .package(url: "https://github.com/nalexn/ViewInspector", from: "0.9.7")
+        .package(url: "https://github.com/nalexn/ViewInspector", from: "0.9.7"),
+        .package(url: "https://github.com/apple/swift-docc-plugin", from: "1.3.0")
     ],
     targets: [
         .target(