gh-101100: Fix Sphinx reference warnings in the glossary (#114729)

Co-authored-by: Alex Waygood <[email protected]>

Author: smontanaro

Doc/glossary.rst

@@ -341,7 +341,7 @@ Glossary
    docstring
       A string literal which appears as the first expression in a class,
       function or module.  While ignored when the suite is executed, it is
-      recognized by the compiler and put into the :attr:`__doc__` attribute
+      recognized by the compiler and put into the :attr:`!__doc__` attribute
       of the enclosing class, function or module.  Since it is available via
       introspection, it is the canonical place for documentation of the
       object.
@@ -1104,10 +1104,12 @@ Glossary
       The :class:`collections.abc.Sequence` abstract base class
       defines a much richer interface that goes beyond just
       :meth:`~object.__getitem__` and :meth:`~object.__len__`, adding
-      :meth:`count`, :meth:`index`, :meth:`~object.__contains__`, and
+      :meth:`!count`, :meth:`!index`, :meth:`~object.__contains__`, and
       :meth:`~object.__reversed__`. Types that implement this expanded
       interface can be registered explicitly using
-      :func:`~abc.ABCMeta.register`.
+      :func:`~abc.ABCMeta.register`. For more documentation on sequence
+      methods generally, see
+      :ref:`Common Sequence Operations <typesseq-common>`.
 
    set comprehension
       A compact way to process all or part of the elements in an iterable and