Split checking of docs in CI

And use stable Rust again for the Check jobs.

.github/workflows/main.yml

@@ -59,14 +59,12 @@ jobs:
         target: ["aarch64-apple-ios", "aarch64-linux-android", "x86_64-apple-darwin", "x86_64-fuchsia", "x86_64-pc-windows-msvc", "x86_64-pc-solaris", "x86_64-unknown-freebsd", "x86_64-unknown-illumos", "x86_64-unknown-linux-gnu", "x86_64-unknown-netbsd", "x86_64-unknown-redox"]
     steps:
     - uses: actions/checkout@v3
-    - uses: dtolnay/rust-toolchain@nightly # NOTE: need nightly for `doc_cfg` feature.
+    - uses: dtolnay/rust-toolchain@stable
       with:
         targets: ${{ matrix.target }}
     - uses: taiki-e/install-action@cargo-hack
     - name: Run check
       run: cargo hack check --feature-powerset --all-targets --examples --bins --tests --target ${{ matrix.target }}
-    - name: Check docs for docs.rs
-      run: RUSTDOCFLAGS="-D warnings --cfg docsrs" cargo doc --no-deps --all-features --target ${{ matrix.target }}
   Clippy:
     name: Clippy
     runs-on: ubuntu-latest
@@ -75,3 +73,19 @@ jobs:
     - uses: dtolnay/rust-toolchain@stable
     - name: Run Clippy
       run: cargo clippy --all-targets --all-features -- -D warnings
+  Docs:
+    name: Docs
+    runs-on: ubuntu-latest
+    strategy:
+      fail-fast: false
+      matrix:
+        # NOTE: missing "x86_64-fuchsia", nightly unavailable at the time of
+        # writing.
+        target: ["aarch64-apple-ios", "aarch64-linux-android", "x86_64-apple-darwin", "x86_64-pc-windows-msvc", "x86_64-pc-solaris", "x86_64-unknown-freebsd", "x86_64-unknown-illumos", "x86_64-unknown-linux-gnu", "x86_64-unknown-netbsd", "x86_64-unknown-redox"]
+    steps:
+    - uses: actions/checkout@v3
+    - uses: dtolnay/rust-toolchain@nightly # NOTE: need nightly for `doc_cfg` feature.
+      with:
+        targets: ${{ matrix.target }}
+    - name: Check docs for docs.rs
+      run: RUSTDOCFLAGS="-D warnings --cfg docsrs" cargo doc --no-deps --all-features --target ${{ matrix.target }}