Close #18980: Enum doc fixes. Patch from Elazar Gershuni.

Doc/library/enum.rst

@@ -38,7 +38,8 @@ follows::
     ...     blue = 3
     ...
 
-..note: Nomenclature
+.. note:: Nomenclature
+
   - The class :class:`Color` is an *enumeration* (or *enum*)
   - The attributes :attr:`Color.red`, :attr:`Color.green`, etc., are
     *enumeration members* (or *enum members*).
@@ -474,7 +475,7 @@ Some rules:
 4. %-style formatting:  `%s` and `%r` call :class:`Enum`'s :meth:`__str__` and
    :meth:`__repr__` respectively; other codes (such as `%i` or `%h` for
    IntEnum) treat the enum member as its mixed-in type.
-5. :class:`str`.:meth:`__format__` (or :func:`format`) will use the mixed-in
+5. :meth:`str.__format__` (or :func:`format`) will use the mixed-in
    type's :meth:`__format__`.  If the :class:`Enum`'s :func:`str` or
    :func:`repr` is desired use the `!s` or `!r` :class:`str` format codes.