Update build.yml

Author: torresc24

.github/workflows/build.yml

@@ -20,5 +20,10 @@ jobs:
         uses: actions/setup-node@v2
         with:
           node-version: ${{ matrix.node-version }}
+      - name: Cache node_modules
+        uses: actions/cache@v2
+        with:
+          path: '**/node_modules'
+          key: ${{ runner.os }}-modules-${{ hashFiles('**/yarn.lock') }}
       - name: Before deploy
         run: npm run docs