fix docs about renamed attributes

Author: infmagic2047

src/doc/en/thematic_tutorials/coercion_and_categories.rst

@@ -106,7 +106,6 @@ This base class provides a lot more methods than a general parent::
 
     sage: [p for p in dir(Field) if p not in dir(Parent)]
     ['__fraction_field',
-     '__ideal_monoid',
      '__iter__',
      '__len__',
      '__rxor__',
@@ -119,6 +118,7 @@ This base class provides a lot more methods than a general parent::
      '_default_category',
      '_gens',
      '_ideal_class_',
+     '_ideal_monoid',
      '_latex_names',
      '_list',
      '_one_element',

src/doc/en/thematic_tutorials/tutorial-objects-and-classes.rst

@@ -298,7 +298,7 @@ http://docs.python.org/library/ for a complete list. ::
         sage: el
         bla
         sage: el.__dict__
-        {'__custom_name': 'bla', 'value': 42}
+        {'_custom_name': 'bla', 'value': 42}
 
     Lots of Sage objects are not Python objects but compiled Cython
     objects. Python sees them as builtin objects and you do not have