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Issue description

 Description:  Section 3.6 step 5 of the text, and the accompanying section of the video, are all over the place. The opening paragraph refers to a 'public-network.conf' file, when it probably means the osd-cluster-network.conf file. The first code section also refers to 'public network' when it seems to intend to mean 'cluster network'. Also at 2:22 in the video the instructor refers to the public network after typing out 'cluster network. It would also be nice if someone explained that the text file doesn't need the underscore in typing out 'cluster network' even though the variable is cluster_network, because that looks like a typo as well, but isn't.

ALSO the instructor is setting cluster_network to 172.25.249.0/24, but it's easy to confuse this with the public_network setting of 172.25.250.0/24 becasuse of the confusion in the code section I already mentioned. I haven't even got past this bit so I might have more feedback afterwards!! 

Steps to reproduce:

Checked on the video section and on the time stamp 2.22 the instructor did mention public network. 

Expected result: