collection roles dont support plugins (#79243)

docs/docsite/rst/collections_guide/collections_using_playbooks.rst

@@ -112,6 +112,8 @@ A few recommendations when creating such playbooks, ``hosts:`` should be generic
 This will have an implied entry in the ``collections:`` keyword of ``my_namespace.my_collection`` just as with roles.
 
 .. note::
-    Playbook names, like other collection resources, have a restricted set of valid characters.
-    Names can contain only lowercase alphanumeric characters, plus _ and must start with an alpha character. The dash ``-`` character is not valid for playbook names in collections.
-    Playbooks whose names contain invalid characters are not addressable: this is a limitation of the Python importer that is used to load collection resources.
+    * Playbook names, like other collection resources, have a restricted set of valid characters.
+      Names can contain only lowercase alphanumeric characters, plus _ and must start with an alpha character. The dash ``-`` character is not valid for playbook names in collections.
+      Playbooks whose names contain invalid characters are not addressable: this is a limitation of the Python importer that is used to load collection resources.
+
+    * Playbooks in collections do not support 'adjacent' plugins, all plugins must be in the collection specific directories.

docs/docsite/rst/playbook_guide/playbooks_reuse_roles.rst

@@ -535,6 +535,9 @@ To use ``allow_duplicates: true`` with role dependencies, you must specify it fo
 Embedding modules and plugins in roles
 ======================================
 
+.. note::
+    This applies only to standalone roles. Roles in collections do not support plugin embedding; they must use the collection's ``plugins`` structure to distribute plugins.
+
 If you write a custom module (see :ref:`developing_modules`) or a plugin (see :ref:`developing_plugins`), you might wish to distribute it as part of a role. For example, if you write a module that helps configure your company's internal software, and you want other people in your organization to use this module, but you do not want to tell everyone how to configure their Ansible library path, you can include the module in your internal_config role.
 
 To add a module or a plugin to a role: