update readme

README.md

@@ -1,2 +1,40 @@
+![logo](coveralls.svg)
+
 # drone-coveralls
+
+
+[![BuildStatus](https://cat.eming.li/api/badges/lizheming/drone-coveralls/status.svg)](https://cat.eming.li/lizheming/drone-coveralls)
+[![Coverage Status](https://coveralls.io/repos/github/lizheming/drone-coveralls/badge.svg?branch=master)](https://coveralls.io/github/lizheming/drone-coveralls?branch=master)
+[![Docker Pulls](https://img.shields.io/docker/pulls/lizheming/drone-coveralls.svg)]()
+[![](https://images.microbadger.com/badges/image/lizheming/drone-coveralls.svg)](https://microbadger.com/images/lizheming/drone-coveralls)
+
 Drone plugin for pushing test coverage to coveralls
+
+This plugin allows for pushing test coverage results to [Coveralls.io](https://coveralls.io).
+
+## Configuration
+First of all you should set environment `COVERALLS_REPO_TOKEN` for plugin. And the following parameters are used to configure the plugin:
+
+files: list of target files to upload. Required.
+token: if you have not set environment `COVERALLS_REPO_TOKEN`, you should set the private repository token.
+debug: debug mode, defaults to false.
+
+### Drone configuration examples
+
+```yaml
+steps:
+- name: test
+  image: node:alpine
+  commands:
+  - npm install
+  - npm run test -- --reporter=text-lcov > ./lcov.info
+
+- name: coveralls
+  image: lizheming/drone-coveralls
+  environment:
+    COVERALLS_REPO_TOKEN:
+      from_secret: coveralls_token
+  settings:
+    files:
+    - ./lcov.info
+```