extend the README description

Author: Ralf Senderek

README.md

@@ -1,2 +1,12 @@
 # cryptlib-tools
- AES file encryption tool and a public/private key management tool based on Cryptlib
+ cryptlib-tools is a collection of single stand-alone tools, that cover all aspects
+ of one specific encryption problem, be it conventional symmetric file encryption (AES),
+ public key management, RSA encryption, email message encryption (S/MIME),
+ CA services or SSH and TLS sessions.
+ 
+ All cryptlib-tools, the AES file encryption tool (claes), the public/private key management
+ tool (clkeys) and the public key encryption tool (clsmime) are based on Cryptlib and are
+ coded in Python3.
+
+ All cryptlib tools can replace complex OpenSSL code by using Cryptlib and are designed
+ to interoperate with programs that are widely used and established like gpg2 and openssl.