[pve-devel] Online Help for complex PVE panels

[Emmanuel Kasper]

Hi

Some Input panels in PVE are quite complex, with a number of options
which can leave the user at doubt. Even if it safe to usually choose
the default, the time to make a decision is proportional to the number
of choices available. A correct understanding of options require 
some active googling and sometimes it is not enough
( example forum thread 
https://forum.proxmox.com/threads/create-vm-hard-disk-option.24180/#post-121578)

Since we have now a user manual with version control, distributed with pve-manager 
we can now document *some* of the more-obscure-but-interesting options in the user manual
and add an help button with a link to that.

The following patch serie adds an optional parameter for the GUI input
panel, onlineHelp: which can be used to add a link to a chapter of 
the pve manual.