How to add a 'how-to' page for clients in the backend

[yojoe]

Thank you for this. Works great!
I think you forgot to change 'pages' into 'wj_userguide_tab' at register_plugin.
And perhaps add a add_action ('wj_userguide_sidebar ...) just cause it looks nicer with a side-bar on the right

Moving user to pages is only a temporary solution, so the user could have access to page's navigation.
The guide page should have 100% width of parent container w/o any additional info, as I don't think there is any need sidebar menu items, if I'd like to ultimately load the page in a modal window.
Unfortunately I'm not sure how to change body's ID from default "#load" value to stylize whole container, as I haven't found any info about that.