Variable defining the path of help directories
BEWARE: This variable must NOT be modified by users.
The global variable %helps is an N x 2 matrix of strings. The kth row of %helps, %helps(k,:) represents the kth chapter of the manual and is made of two strings:
%helps(k,1) is the absolute pathname for a help directory.
%helps(k,2) is a title for this help directory.
To add a new help directory, the user should use add_help_chapter.