Update README.mkd

Author: paulocheque

README.mkd

@@ -71,7 +71,7 @@ Cheat Sheet
 
 ```python
 # Import the main DDF features
-from ddf import N, G, F, M, C, P, teach
+from ddf import N, G, F, M, C, P, teach # meaning: New, Get, ForeignKey, Mask, Copier, Print, teach
 ```
 
 ```python
@@ -101,13 +101,13 @@ assert instance.address == 'Street TPA, 632 - BR'
 
 ```python
 # `C` copies data from one field to another
-instance = N(Book, address_formatted=C('address'), address=D('Street ___, ### \- --'))
+instance = N(Book, address_formatted=C('address'), address=M('Street ___, ### \- --'))
 assert instance.address_formatted == 'Street TPA, 632 - BR'
 ```
 
 ```python
 # `teach` teaches DDF in how to build an instance
-teach(Book, address=M'Street ___, ### !- --'))
+teach(Book, address=M('Street ___, ### !- --'))
 instance = G(Book)
 assert instance.address == 'Street TPA, 632 - BR'
 ```