Use stable for building docs.

.github/workflows/main.yml

@@ -48,6 +48,9 @@ jobs:
     - uses: actions/checkout@v2
       with:
         submodules: true
+    - uses: ./.github/actions/install-rust
+      with:
+        toolchain: stable
     - run: |
         set -e
         curl -L https://github.com/rust-lang-nursery/mdBook/releases/download/v0.4.4/mdbook-v0.4.4-x86_64-unknown-linux-gnu.tar.gz | tar xzf -
@@ -67,17 +70,15 @@ jobs:
     name: Doc - build the API documentation
     runs-on: ubuntu-latest
     env:
-      RUSTDOCFLAGS: -Dbroken_intra_doc_links --cfg nightlydoc
+      RUSTDOCFLAGS: -Dbroken_intra_doc_links
       OPENVINO_SKIP_LINKING: 1
     steps:
     - uses: actions/checkout@v2
       with:
         submodules: true
-    # Note that we use nightly Rust here to get intra-doc links which are a
-    # nightly-only feature right now.
     - uses: ./.github/actions/install-rust
       with:
-        toolchain: nightly
+        toolchain: stable
     - run: cargo doc --no-deps --all --exclude wasmtime-cli --exclude test-programs --exclude cranelift-codegen-meta
     - run: cargo doc --package cranelift-codegen-meta --document-private-items
     - uses: actions/upload-artifact@v1