added caching to pipeline

.drone.yml

@@ -2,6 +2,17 @@ kind: pipeline
 name: default
 
 steps:
+
+- name: restore cache
+  image: drillster/drone-volume-cache
+  settings:
+    restore: true
+    mount:
+      - ./node_modules
+  volumes:
+  - name: cache
+    path: /cache
+
 - name: npm install
   image: node:12
   commands:
@@ -12,6 +23,16 @@ steps:
   commands:
   - npm run build
 
+- name: rebuild cache
+  image: drillster/drone-volume-cache
+  settings:
+    rebuild: true
+    mount:
+      - ./node_modules
+  volumes:
+  - name: cache
+    path: /cache
+
 - name: deliver container
   image: plugins/docker
   settings:
@@ -60,4 +81,9 @@ steps:
       from_secret: docker_password
   when:
     event:
-    - tag
+    - tag
+    
+volumes:
+- name: cache 
+  host:
+    path: /tmp