Improve ch_messaging-security.xml

Use markup for passwords and indicate that it should be replaced.
Add missing line in programlisting.
Change IP to all-caps.
Rewrap all paragraphs to avoid overlong lines.

Change-Id: I13a210dcdf876312aa4803781ec6131339168a4b
Closes-Bug: #1342439
Merge "Improve ch_messaging-security.xml"