update readme

Author: rzcoder

README.md

@@ -214,6 +214,7 @@ Questions, comments, bug reports, and pull requests are all welcome.
 ### 0.2.20
  * Added `.encryptPrivate()` and `.decryptPublic()` methods
  * Encrypt/decrypt methods in nodejs 0.12.x and io.js using native implementation (> 40x speed boost)
+ * Fixed some regex issue causing catastrophic backtracking.
  * *KNOWN ISSUE*:`encryptPrivate` and `decryptPublic` don't have native implementation in nodejs and can't be use in native implementation with pkcs1_oaep padding in io.js
 
 ### 0.2.10