ci: fix docs ci cache key (#82)

Signed-off-by: longjin <longjin@dragonos.org>

.github/workflows/docs.yml

@@ -25,7 +25,7 @@ jobs:
         cache-name: cache-node-modules
       with:
         path: ./docs/node_modules
-        key: ${{ runner.os }}-build-${{ env.cache-name }}-${{ hashFiles('package.json') }}
+        key: ${{ runner.os }}-build-${{ env.cache-name }}-${{ hashFiles('docs/package.json') }}-${{ hashFiles('docs/package-lock.json') }}
 
     - name: echo node version
       working-directory: ./docs