Missing user and database setup on Install and configure (Red Hat) in glance

[somat]

- [x] This is a doc addition request.
- [x] I have a fix to the document that I can paste below including example: input and output.

In the documentation it seems like instruction for user and database creation for Glance are missing.

MariaDB [(none)]> CREATE DATABASE glance;
Query OK, 1 row affected (0.00 sec)

MariaDB [(none)]> GRANT ALL PRIVILEGES ON glance.* TO 'glance'@'localhost' \
    -> IDENTIFIED BY 'GLANCE_DBPASS';
Query OK, 0 rows affected (0.00 sec)

MariaDB [(none)]> GRANT ALL PRIVILEGES ON glance.* TO 'glance'@'%' \
    -> IDENTIFIED BY 'GLANCE_DBPASS';
Query OK, 0 rows affected (0.00 sec)

-----------------------------------
Release: 15.0.1.dev1 on 'Mon Aug 7 01:28:54 2017, commit 9091d26'
SHA: 9091d262afb120fd077bae003d52463f833a4fde
Source: https://git.openstack.org/cgit/openstack/glance/tree/doc/source/install/install-rdo.rst
URL: https://docs.openstack.org/glance/pike/install/install-rdo.html

[Berk CELEBI (berkcelebi)]

this is also same for other operating systems installation pages as well.