Pedantic change

README.md

@@ -9,7 +9,7 @@ Provides a tabbed interface for editing and testing GraphQL queries/mutations wi
 
 #### Installation
 
-If you have [Homebrew](http://brew.sh/) installed on OSX:
+If you have [Homebrew](http://brew.sh/) installed on macOS:
 
 ```
 brew cask install graphiql
@@ -23,4 +23,4 @@ Alternately, download the binary from the [Releases](https://github.com/skevy/gr
 - cd into it
 - install all the require packages: `npm i`
 - build the project: `npm run build`
-- start the project: `npm start`
+- start the project: `npm start`