Change large scale -> large-scale

README.md

@@ -7,11 +7,11 @@
 
 ## Motivation
 
-> Learn how to design large scale systems.
+> Learn how to design large-scale systems.
 >
 > Prep for the system design interview.
 
-### Learn how to design large scale systems
+### Learn how to design large-scale systems
 
 Learning how to design scalable systems will help you become a better engineer.