Minor documentation changes #1

Author: nemothenoone

docs/introduction.md

@@ -1,7 +1,7 @@
 # Message Authentication Codes Introduction # {#mac_introduction}
 
-The Crypto3.MAC library extends the Nil Foundation's cryptography suite and provides a set of key derivation
- functions implemented in way C++ standard library implies: concepts, algorithms, predictable behavior, latest standard features support and clean architecture without compromising security and performance.
+The Crypto3.MAC library extends the Nil Foundation's cryptography suite and provides a set of message
+ authentication codes implemented in way C++ standard library implies: concepts, algorithms, predictable behavior, latest standard features support and clean architecture without compromising security and performance.
 
 Crypto3.MAC consists of several parts to review:
 * [Manual](@ref mac_manual).