Fix typo in docstring and minor formatting (#336)

Author: carsonip

MySQLdb/_mysql.c

@@ -732,7 +732,7 @@ _mysql_ConnectionObject_commit(
 }
 
 static char _mysql_ConnectionObject_rollback__doc__[] =
-"Rolls backs the current transaction\n\
+"Rolls back the current transaction\n\
 ";
 static PyObject *
 _mysql_ConnectionObject_rollback(

MySQLdb/cursors.py

@@ -471,7 +471,7 @@ class Cursor(CursorStoreResultMixIn, CursorTupleRowsMixIn,
 
 class DictCursor(CursorStoreResultMixIn, CursorDictRowsMixIn,
                  BaseCursor):
-     """This is a Cursor class that returns rows as dictionaries and
+    """This is a Cursor class that returns rows as dictionaries and
     stores the result set in the client."""