[Samba] Wiki should have Readme First

[Klaus Hartnegg]

Many first time users of Samba-4 seem to struggle with the same issues.

I suggest the Wiki should have a Readme First similar like this:
http://www.klaus-hartnegg.de/gpo/14-03-12-samba4.html

It basicly says that Samba 4 can behave either like Samba 3, or as 
AD-DC, in which case it should do nothing else. Then it lists the main 
differences, limitations, and requirements.

I would love to see a link to such a text on
https://wiki.samba.org/index.php/Main_Page
as first item below "User Documentation".

Comments? Suggestions? Corrections?

Feel free to copy, edit, and put it on the Wiki.

Klaus