Guard against broken intra-doc links in CI (#2616)

.github/workflows/clippy-fmt.yml

@@ -5,6 +5,24 @@ on:
     types: [opened, synchronize, reopened]
 
 jobs:
+  lint-docs:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v2
+      - name: Install Rust
+        uses: actions-rs/toolchain@v1
+        with:
+          toolchain: stable
+          profile: minimal
+          components: rust-docs
+      - name: Check for broken intra-doc links
+        uses: actions-rs/cargo@v1
+        env:
+          RUSTDOCFLAGS: "-D warnings"
+        with:
+          command: doc
+          args: --no-deps --all-features --workspace
+
   fmt:
     runs-on: ubuntu-latest
     steps: