docs/man/upsset.conf.txt: document recommendations about CGI timeout [#3219]

Signed-off-by: Jim Klimov <jimklimov+nut@gmail.com>

Author: jimklimov

docs/man/upsset.conf.txt

@@ -145,6 +145,15 @@ Revise "Handler Mappings" for the `cgi-bin` subdirectory, that it includes
 "CGI-exe" with "Path `*.exe`" and "State Enabled" (if not, edit the entry,
 press "Request Restrictions", and tick "Access/Execute" there).
 
+If the (virtual) server is dedicated to NUT CGI programs, you may also want
+to visit the "CGI" icon, and change Behavior/Timeout to a few minutes or even
+seconds (and Apply the change), so in case of any breakage in the NUT CGI
+programs, you would not stare at a blank page and not know if the server
+is alive. This recommendation may change later if support for "tracking" of
+device-side completion of posted commands or settings would be implemented;
+currently the linkman:upsset[8] CGI client only gets and relays confirmation
+that the NUT data server linkman:upsd[8] received the request.
+
 In the NUT configuration directory, update the linkman:hosts.conf[5] and
 `upsset.conf` files as appropriate, (optionally adapt) and rename the
 `upsstats.html.sample` and `upsstates-single.html.sample` files to not