Remove ref of patrole

patrole project is not maintained and in QA
PTG, we decided to retire it.

- https://etherpad.opendev.org/p/qa-bobcat-ptg

Depends-On: https://review.opendev.org/c/openstack/governance/+/880014
Change-Id: I85f21612446fb9d899326398950f3c8a32747141

README.rst

@@ -27,15 +27,13 @@ The structure of the repository is as follows::
           implemented/
       other
           implemented/
-      patrole
-          implemented/
       tempest
           implemented/
 
 Expected Work Flow
 ==================
 
-1. Create a blueprint stub in ``tempest``,  ``devstack``,  ``patrole`` or ``other``
+1. Create a blueprint stub in ``tempest``,  ``devstack``, or ``other``
    blueprint repository
 2. Propose review to qa-specs repository (ensure bp:blueprint_name is
    in the commit message.  DevStack specs should go into the ``devstack/`` subdirectory

doc/source/index.rst

@@ -25,15 +25,6 @@ DevStack
 
    specs/devstack/*
 
-Patrole
--------
-
-.. toctree::
-   :glob:
-   :maxdepth: 2
-
-   specs/patrole/*
-
 Other
 -----
 

specs/patrole/placeholder.rst

@@ -1,12 +0,0 @@
-..
-  This work is licensed under a Creative Commons Attribution 3.0 Unported
-  License.
-
-  http://creativecommons.org/licenses/by/3.0/legalcode
-
-===========
-Placeholder
-===========
-
-This is just a placeholder file to avoid sphinx errors. Please remove this
-file when you add a new rst file.