Fixed typo in README

Author: ShiroTohu

README.md

@@ -9,7 +9,7 @@ The +2 Bot is a Discord bot that tracks the number of +2s and -2s among users.
 This bot was inspired by Jerma's stream where he and Etalyx set out to beat Kane and Lynch 2: Dog Days in just under four hours. For every funny joke they made, two minutes were added to the timer; for every unfunny joke, two minutes were subtracted. The chat would spam "+2" or "-2" to voice their opinions on whether a joke was good or bad. Jerma and Etalyx beat the game with just 45 seconds remaining.
 
 ## Installation
-This bot is supported by all major operating system
+This bot is supported by all major operating systems
 
  - [Windows](./docs/installation/Windows.md)
  - [MacOS](./docs/installation/MacOS.md)