Small typo fixed

Author: izshreyansh

README.md

@@ -38,7 +38,7 @@ Of course you will probably want a position column as well. So you will have to
 
 ## Change the name of subcollections
 
-BBy default, the name of the subcollections is **items**, but you can change it by calling the ```childrenName($name)``` method :
+By default, the name of the subcollections is **items**, but you can change it by calling the ```childrenName($name)``` method :
 For example if you want your subcollections being named **children**:
 
 ```php