Verify connectivity in Installation Guide

[sharif uddin]

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:

- [x ] 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: input and output.

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Release: on 2022-11-09 13:01:49
SHA: ca3af8eba4011c4b63f8b03a8769e012532b6451
Source: https://opendev.org/openstack/openstack-manuals/src/doc/install-guide/source/environment-networking-verify.rst
URL: https://docs.openstack.org/install-guide/environment-networking-verify.html

ping -c 4 openstack.org

should be

ping -c 4 docs.openstack.org