feat(build): enhance license file packaging logic and add Rust toolchain setup in docs workflow

.github/workflows/docs.yml

@@ -25,6 +25,11 @@ jobs:
     steps:
       - uses: actions/checkout@v6
 
+      - uses: actions-rust-lang/setup-rust-toolchain@v1
+        with:
+          toolchain: stable
+          cache: true
+
       - name: Cache mdbook
         id: cache-mdbook
         uses: actions/cache@v5