Misc doc improvements and fixes (#59)

- Fix broken doc link and improve how linking is implemented
- Add CI to prevent future broken links
- Update docs referencing `VersionedMigration`

Note the additional dependencies are already pulled in as deps to
existing packages, so does not add to the build.

.github/workflows/rust-checks.yaml

@@ -16,6 +16,24 @@ env:
   TOOLCHAIN_LINT: nightly-2023-11-13
 
 jobs:
+  doc:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+      - name: Install Rust ${{ env.TOOLCHAIN_LINT }}
+        uses: dtolnay/rust-toolchain@stable
+        with:
+          targets: wasm32-unknown-unknown
+      - uses: Swatinem/rust-cache@v2
+        with:
+          key: check-doc-v0
+      - name: Install Protoc
+        uses: arduino/setup-protoc@v1
+        with:
+          version: "3.6.1"
+      - name: cargo doc
+        run: RUSTFLAGS="-D warnings" cargo doc
+
   lint:
     runs-on: ubuntu-latest
     steps: