Update "auth_url" in install docs
Update "auth_url" in install docs

Following the change in Keystone Install Guide [1],
this patch replace port 35357 with 5000 for "auth_url" in docs.

For more details, please check similar changes which have been done
on other projects: Nova [2], Neutron [3], Cinder [4], Glance [5].

[1] https://review.openstack.org/#/c/541857
[2] https://review.openstack.org/#/c/562812
[3] https://review.openstack.org/#/c/566491
[4] https://review.openstack.org/#/c/565464
[5] https://review.openstack.org/#/c/558932

Change-Id: I96c45181c344ab78fa33f6fe05f6d898732fb780

openstack/aodh,openstack/aodh