update READMEs

exercises/isbn-verifier/README.md

-# Isbn Verifier
+# ISBN Verifier
 
 The [ISBN-10 verification process](https://en.wikipedia.org/wiki/International_Standard_Book_Number) is used to validate book identification
 numbers. These normally contain dashes and look like: `3-598-21508-8`

exercises/reverse-string/README.md

-# reverse-string
+# Reverse String
 
 Reverse a string
 

exercises/rna-transcription/README.md

 
 ## Source
 
-Rosalind [http://rosalind.info/problems/rna](http://rosalind.info/problems/rna)
+Hyperphysics [http://hyperphysics.phy-astr.gsu.edu/hbase/Organic/transcription.html](http://hyperphysics.phy-astr.gsu.edu/hbase/Organic/transcription.html)
 
 ## Submitting Incomplete Solutions