[Install Guide] Update keystone install
[Install Guide] Update keystone install

Symlink to wsgi-keystone.conf instead of creating
a new file.

Minor RST syntax fixes.

Change-Id: I8455c327d9b2d08c808d8c5ca5a3648aa27cc021

openstack/openstack-manuals,openstack/openstack-manuals,openstack/openstack-manuals,openstack/openstack-manuals