[DOCS] - Removing tags: and category:

Change-Id: I706a7c99afa6ca1d2243878394f02dae192d6117

CONTRIBUTING.rst

@@ -1,7 +1,5 @@
 OpenStack LXC host setup
 ########################
-:tags: openstack, lxc, host, cloud, ansible
-:category: \*nix
 
 contributor guidelines
 ^^^^^^^^^^^^^^^^^^^^^^
@@ -32,7 +30,7 @@ Pull requests submitted through GitHub will be ignored and closed without regard
 Extra
 -----
 
-Tags: 
+Tags:
     If it's a bug that needs fixing in a branch in addition to Master, add a '\<release\>-backport-potential' tag (eg ``juno-backport-potential``).  There are predefined tags that will autocomplete.
 
 Status:
@@ -45,7 +43,7 @@ Importance:
 Style guide
 -----------
 
-When creating tasks and other roles for use in Ansible please create then using the YAML dictionary format. 
+When creating tasks and other roles for use in Ansible please create then using the YAML dictionary format.
 
 Example YAML dictionary format:
     .. code-block:: yaml