Merge pull request #40 from seek-oss/readme-docker-plugin

Update referenced version of docker plugin

Author: 72636c

README.md

@@ -28,7 +28,7 @@ steps:
   - command: echo wow
     plugins:
       - seek-oss/docker-ecr-cache#v2.0.0
-      - docker#v3.11.0
+      - docker#v3.12.0
 ```
 
 ### Caching npm packages
@@ -56,7 +56,7 @@ steps:
           cache-on:
             - package.json # avoid cache hits on stale lockfiles
             - package-lock.json
-      - docker#v3.11.0:
+      - docker#v3.12.0:
           volumes:
             - /workdir/node_modules
 ```
@@ -86,7 +86,7 @@ steps:
     plugins:
       - seek-oss/docker-ecr-cache#v2.0.0:
           dockerfile: my-dockerfile
-      - docker#v3.11.0
+      - docker#v3.12.0
 ```
 
 Alternatively, Dockerfile can be embedded inline:
@@ -102,7 +102,7 @@ steps:
             COPY package.json package-lock.json /workdir
             RUN npm install
 
-      - docker#v3.11.0
+      - docker#v3.12.0
 ```
 
 ### Building on the resulting image
@@ -154,7 +154,7 @@ steps:
     plugins:
       - seek-oss/docker-ecr-cache#v2.0.0:
           target: build-deps
-      - docker#v3.11.0
+      - docker#v3.12.0
 ```
 
 ### Specifying build context
@@ -170,7 +170,7 @@ steps:
       - seek-oss/docker-ecr-cache#v2.0.0:
           dockerfile: dockerfiles/test/Dockerfile
           context: '.'
-      - docker#v3.11.0
+      - docker#v3.12.0
 ```
 
 ### Specifying build args
@@ -200,7 +200,7 @@ steps:
           build-args:
             - ARG_1
             - ARG_2=such
-      - docker#v3.11.0
+      - docker#v3.12.0
 ```
 
 Additional `docker build` arguments be passed via the `additional-build-args` setting:
@@ -213,7 +213,7 @@ steps:
     plugins:
       - seek-oss/docker-ecr-cache#v2.0.0:
           additional-build-args: '--ssh= default=\$SSH_AUTH_SOCK'
-      - docker#v3.11.0
+      - docker#v3.12.0
 ```
 
 ### Specifying secrets
@@ -242,7 +242,7 @@ steps:
       - seek-oss/docker-ecr-cache#v2.0.0:
           secrets:
             - SECRET
-      - docker#v3.11.0
+      - docker#v3.12.0
 ```
 
 You can also specify the full `--secret` flag value if you need more control:
@@ -258,7 +258,7 @@ steps:
       - seek-oss/docker-ecr-cache#v2.0.0:
           secrets:
             - id=npmrc,src=.npmrc
-      - docker#v3.11.0
+      - docker#v3.12.0
 ```
 
 You must have a recent version of Docker with BuildKit support to use secrets.
@@ -275,7 +275,7 @@ steps:
     plugins:
       - seek-oss/docker-ecr-cache#v2.0.0:
           max-age-days: 7
-      - docker#v3.11.0
+      - docker#v3.12.0
 ```
 
 ### Changing the name of exported variable
@@ -308,7 +308,7 @@ steps:
           ecr-tags:
             Key: Value
             Key2: Value2
-      - docker#v3.11.0
+      - docker#v3.12.0
 ```
 
 #### Specifying a region
@@ -321,7 +321,7 @@ steps:
     plugins:
       - seek-oss/docker-ecr-cache#v2.0.0:
           region: ap-southeast-2
-      - docker#v3.11.0
+      - docker#v3.12.0
 ```
 
 #### Required permissions