Mistake in masakari installation guide

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I haven't installed and configured Masakari myself yet, I was just browsing the docs and found an inconsistency, more details below.

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.
- [X] I have a fix to the document that I can paste below including example:

The overview page states that it's for the compute node:

> This section describes how to install and configure Masakari services on the compute node.

While the installation page [1] has a clear note that the installation is only for control nodes:

> You must install Masakari on the Controller Nodes only.

[1] https://docs.openstack.org/masakari/latest/install/install_and_configure_ubuntu.html

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-----------------------------------
Release: 15.1.0.dev4 on 2019-10-03 16:45:41
SHA: b2f2a58e3c3b4cdb3801e1d09b0a1f5aa62fc4ce
Source: https://opendev.org/openstack/masakari/src/doc/source/install/install_and_configure.rst
URL: https://docs.openstack.org/masakari/latest/install/install_and_configure.html