docs:Install glance on centos, something missed

[lxf]

miss create database glance part, when i upload a image, report 500 error ,please add create database part in the docs.

This bug tracker is for errors with the documentation, use the following as a template and remove or add fields as you see fit. Convert [ ] into [x] to check boxes:

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

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-----------------------------------
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

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: stable/pike
Review: https://review.openstack.org/508279

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/508279
Committed: https://git.openstack.org/cgit/openstack/glance/commit/?id=06af2eb5abe0332f7035a7d7c2fbfd19fbc4dae7
Submitter: Zuul
Branch: stable/pike

commit 06af2eb5abe0332f7035a7d7c2fbfd19fbc4dae7
Author: ericxiett <[e-mail]>
Date: Tue Sep 19 16:50:14 2017 +0800

    Fix missing some content of glance database creation.

    The indentation of glance database creation was incorrect.
    This patch fixes it.

    Change-Id: If3ca607258363f5b6e8e1b86e0425fd74da2e62a
    Closes-Bug: #1718125
    Closes-Bug: #1720108
    (cherry picked from commit 2f8edeedc88491214d2502c5b1d17a155f452a47)

[OpenStack Infra (hudson-openstack)]

This issue was fixed in the openstack/glance 15.0.1 release.