Update README.md

Author: James

Diff for: README.md

@@ -2,6 +2,30 @@
 
 This is a javascript library to interact with commitground platform.
 
+# Contributing
+
+## Prerequisites
+
+1. Load submodules
+
+    ```.bash
+    git submodule update --init --recursive
+    ```
+
+1. Install truffle
+
+    ```.bash
+    npm install -g truffle
+    ```
+    You can read truffle install doc [here](https://truffleframework.com/docs/getting_started/installation)
+
+1. Ganache(One click ethereum private net).
+
+    Two options exist. When you run this repository on your local environment, desktop app will help you know what's happening on the blockchain. But for the CI/CD environment, 'ganache-cli' will be a better option.
+    - [ganache-cli](https://github.com/trufflesuite/ganache-cli)
+    - [ganache desktop app](https://truffleframework.com/ganache)
+
+
 # Contributors
 [Wanseob Lim](https://github.com/james-lim)