Add Lecture 10 slides.

README.md

@@ -14,6 +14,7 @@ June 29 - September 23, 2015; Chicago, IL
 * [Lab 2 on August 5](https://docs.google.com/presentation/d/1nv-O59Jot9RRFJauLLXV4PewDf4pjo7nbafxG6x-jqw/edit?usp=sharing). Covered: modules and namespacing, applicative parsing with ```parsec```, a monad-transformer stack (```Lisp``` monad), and sets and maps (```Data.Set```, ```Data.Map```).
 * [Lecture 8 on August 13](https://docs.google.com/presentation/d/11QAjAvUV9aVDajOqUeNp2jQPdHd5_s1dQs73nY5sxOo/edit?usp=sharing). Covered: ```Foldable``` and ```Traversable```, plus a potpourri of language extensions (including ```MultiParamTypeClasses``` and ```FunctionalDependencies```.)
 * [Lecture 9 on August 17](https://docs.google.com/presentation/d/1U9uoaQEoKAjcegPEVFTNSIKv92jhqkkz9qVeBFzr4kY/edit?usp=sharing). Covered: IO, files and ```Handle```, error-handling and the ```Exception``` type-class. Also, ```IORef``` and ```MVar```. 
+* [Lecture 10 on September 9](https://docs.google.com/presentation/d/1ZK52BJgDJgG-tfsswp5f-h-fXi0TMwsKdFo1B5AssJM/edit#slide=id.gb94c3e4a0_0_0). Covered: Lenses! (Also, Prisms and Traversals, very briefly.)
 
 ## Lecture videos
 * [Lecture 1 video](https://www.youtube.com/watch?v=ZoBOUqS1jgI)