add photo to readme.md code example
Example 1: add image to readme
![alt text](http://url/to/img.png)
Example 2: how to add image in readme.md
![alt text](https://github.com/[username]/[reponame]/blob/[branch]/image.jpg?raw=true)
![alt text](http://url/to/img.png)
![alt text](https://github.com/[username]/[reponame]/blob/[branch]/image.jpg?raw=true)