Name of the main help file. All distributed help files should be placed together in one directory. Additionally, all "doc" directories in 'runtimepath' will be used. Environment variables are expanded :set_env. For example: "$VIMRUNTIME/doc/help.txt". If $VIMRUNTIME is not set, $VIM is also tried. Also see $VIMRUNTIME and option-backslash about including spaces and backslashes. This option cannot be set from a modeline or in the sandbox, for security reasons.

(default (MS-Windows) "$VIMRUNTIME\doc\help.txt" (others) "$VIMRUNTIME/doc/help.txt")