Fix plugin-list label and script

This was changed during the current docs restructing and
we missed that it changed the label.

doc/en/reference/plugin_list.rst

@@ -1,5 +1,7 @@
-Plugins List
-============
+.. _plugin-list:
+
+Plugin List
+===========
 
 PyPI projects that match "pytest-\*" are considered plugins and are listed
 automatically. Packages classified as inactive are excluded.

scripts/update-plugin-list.py

@@ -6,8 +6,11 @@ import packaging.version
 import requests
 import tabulate
 
-FILE_HEAD = r"""Plugins List
-============
+FILE_HEAD = r"""\
+.. _plugin-list:
+
+Plugin List
+===========
 
 PyPI projects that match "pytest-\*" are considered plugins and are listed
 automatically. Packages classified as inactive are excluded.