[skip ci] Update Go SDK contributing guide (milvus-io#196)

Signed-off-by: LocoRichard <[email protected]>

CONTRIBUTING.md

@@ -1,6 +1,37 @@
-# Contributing to milvus-go-java
+# Contributing to Milvus Go SDK
 
-We welcome all kinds of contributions. Simply file an issue stating your reason
-and plans for making the change, update CHANGELOG.md, and create a pull request 
-to the current active branch. Make sure to refer to the issue you filed in your 
-PR's description. Cheers!:tada:
+Contributions of all kinds and from everyone are welcome. Simply file an issue stating your reason and plans for making the change, update CHANGELOG.md, and create a pull request to the current active branch. Make sure to mention the issue you filed in your PR description. Cheers!
+
+
+## What contributions can I make?
+
+Any contributions are allowed without changing the project architecture and interfaces here.
+You are more than welcome to make contributions.
+
+
+## How can I contribute?
+
+### Development environment
+
+You are recommended to develop using [Go](https://golang.org/dl/). We recommended using version 1.15 in this project.
+
+
+### Coding Style
+
+Please follow the [Milvus Contribution Guide](https://github.com/milvus-io/milvus/blob/master/CONTRIBUTING.md#coding-style).
+
+
+## Run unit test with code coverage
+
+Before submitting your PR, make sure you have the run unit test, and your code coverage rate is >= 80%.
+
+```shell 
+$ ./scripts/run_go_unittest.sh
+```
+
+You may need a Milvus server which is running when you run unit test. See more details on [Milvus server](https://github.com/milvus-io/milvus).
+
+
+## Update CHANGLOG.md
+
+Add issue tips into CHANGLOG.md, make sure all issue tips are sorted by issue number in ascending order.