Update formcrypt obj docstring

Author: wizardy0ga

src/formcrypt/core.py

@@ -41,7 +41,7 @@ class FormCrypt( object ):
     
     :param: keysize
         An int which sets the size of the default encryption key size for all string keys within the 
-        formcrypt source
+        formcrypt source. Default to 16 bytes.
     """
     def __init__(self, strings: dict, keysize = DEFAULT_KEY_SIZE):
         self.source = SourceCode(source_file=FORMCRYPT_SOURCE, filename='formcrypt.c')