Hits about plugin installation and usage

Author: JozoVilcek

README.md

@@ -1,2 +1,32 @@
-Mermaid plugin for GitBook
-==============
+## Mermaid plugin for GitBook 
+[![Build Status](https://travis-ci.org/JozoVilcek/gitbook-mermaid-plugin.svg?branch=master)](https://travis-ci.org/JozoVilcek/gitbook-mermaid-plugin)
+
+Plugin for [GitBook](https://github.com/GitbookIO/gitbook) which renders [Mermaid](https://github.com/knsv/mermaid) diagrams and flow charts detected in the book markdown.
+
+### How to install it?
+
+You can use install via **NPM**:
+
+```
+$ npm install gitbook-mermaid-plugin
+```
+
+And use it for your book with in the book.json:
+
+```
+{
+    "plugins": ["gitbook-mermaid"]
+}
+```
+
+### How to use it?
+
+Just put the code into fenced code block and tag it **mermaid** key word like this:
+```mermaid
+graph TD;
+  A-->B;
+  A-->C;
+  B-->D;
+  C-->D;
+```
+Plugin will pick it up and pack into properly marked div element, where it can be found by mermaid client side rendering.