Update 'README.md'

README.md

@@ -19,7 +19,7 @@
 
 ![PhoneBookDesign](./PhoneBookUML.png)
 
-In this diagram, C stands for Class, f stnads for field, and m stands for method.
+In this diagram, C stands for Class, f stands for field, and m stands for method.
 So, it can give you a specification for the class and the things it needs to do.
 
 * Create a `PhoneBook` class that holds names and phone numbers.