Grammar tweaks in README.md (#33)

Author: coryhouse

README.md

@@ -3,8 +3,8 @@
 [![Greenkeeper badge](https://badges.greenkeeper.io/jest-community/snapshot-diff.svg)](https://greenkeeper.io/)
 [![npm version](https://badge.fury.io/js/snapshot-diff.svg)](https://badge.fury.io/js/snapshot-diff)
 
-Diffing snapshot utility for Jest. Takes two values, and return their difference as a string, ready to be snapshoted with `toMatchSnapshot()`.
-Especially helpful when testing the difference between different states of a React component.
+Diffing snapshot utility for Jest. Takes two values, and return their difference as a string, ready to be snapshotted with `toMatchSnapshot()`.
+Especially helpful when testing the difference between different React component states.
 
 ## Installation
 ```bash