If supplied a topic, then show the appropriate documentation page.
If the topic does not exist, or if multiple terms are provided, then run
the help-search command to find a match. Note that, if help-search
finds a single subject, then it will run help on that topic, so unique
matches are equivalent to specifying a topic name.
Default: "man" on Posix, "browser" on Windows
The program to use to view help content.
Set to "browser" to view html help content in the default web browser.