Update README.md

Author: jamesdbrock

README.md

@@ -107,7 +107,7 @@ stack-safe.
 
 ## Resources
 
-- [*Monadic Parsers at the Input Boundary* (YouTube)](https://www.youtube.com/watch?v=LLkbzt4ms6M) by James Brock is a an introductory tutorial to monadic parser combinators with this package.
+- [*Monadic Parsers at the Input Boundary* (YouTube)](https://www.youtube.com/watch?v=LLkbzt4ms6M) by James Brock is an introductory tutorial to monadic parser combinators with this package.
 
 - [*Monadic Parser Combinators*](https://www.cs.nott.ac.uk/~pszgmh/monparsing.pdf) by Graham Hutton and Erik Meijer 1996.