Update glossary.rst - refer to dependency-specifiers

Author: noamraph

source/glossary.rst

@@ -209,8 +209,8 @@ Glossary
     Requirement Specifier
 
        A format used by :ref:`pip` to install packages from a :term:`Package
-       Index`. For an EBNF diagram of the format, see `PEP 508
-       <https://peps.python.org/pep-0508/>`_. For example, "foo>=1.3" is a
+       Index`. For an EBNF diagram of the format, see :ref:`dependency-specifiers`.
+       For example, "foo>=1.3" is a
        requirement specifier, where "foo" is the project name, and the ">=1.3"
        portion is the :term:`Version Specifier`