Added nice tip to config.h

GhettoCrypt/Config.h

@@ -3,6 +3,9 @@
 
 namespace GhettoCipher
 {
+	// MUST BE A POWER OF 2 > 4
 	constexpr std::size_t BLOCK_SIZE = 512;
+
+	// MUST BE > 2
 	constexpr std::size_t N_ROUNDS = 64;
 }