Bug#484074: New internal commands not documented via man or info

[Dominique Brazziel]

The 'search' command is only documented from the grub command line 
(via 'help search').  The 'linux' command which now includes the
'root=UUID=xxxxxx' construct is not documented anywhere.

The new scripting facility is not documented anywhere in the 
package and only cursorily in the GRUB2 online manual.

The new 'vbeinfo', 'gfxterm' commands and the command list
which aliases these commands needs to be documented in the package.

Basically the user is left to reverse engineer everything in the
package by reading the scripts and the online manual.