Add Alex Knauth as author

Author: jackfirth

lens/main.scrbl

@@ -9,7 +9,8 @@ This library includes functions and forms for working with
 small piece of a larger structure. Think of them as a more general
 representation of getters and setters in object-oriented languages.
 
-@author[@author+email["Jack Firth" "jackhfirth@gmail.com"]]
+@author[@author+email["Jack Firth" "jackhfirth@gmail.com"]
+        @author+email["Alex Knauth" "alexander@knauth.org"]]
 
 source code: @url["https://github.com/jackfirth/lens"]