typo edit

Author: tehfedaykin

Diff for: README.md

@@ -3,4 +3,4 @@ Adds a @diff tag for use in bit-docs.
 @diff takes two file paths and an optional "only" flag. 
 
 The files will be diffed and return the codeblock with the second file's contents with a list of the new lines. 
-To be used in demonstarting changes between files as a tutorial progresses
+To be used in demonstrating changes between files as a tutorial progresses