phosphor-gpio-monitor: fix continue flag

"--continue" is intended to be a flag and not a boolean option[1].

Change the CLI11 call so that we do not need a boolean value for it.

[1]: https://github.com/openbmc/openbmc/blob/master//meta-ibm/meta-romulus/recipes-phosphor/gpio/id-button/obmc/gpio/id_button#L5

Signed-off-by: Patrick Williams <patrick@stwcx.xyz>
Change-Id: I6f870a0b416465e042ed6bf34d62db9be042c394
diff --git a/mainapp.cpp b/mainapp.cpp
index 2496a89..77f8a4d 100644
--- a/mainapp.cpp
+++ b/mainapp.cpp
@@ -46,8 +46,8 @@
     app.add_option("-t,--target", target,
                    "Systemd unit to be called on GPIO state change")
         ->required();
-    app.add_option("-c,--continue", continueRun,
-                   "PWhether or not to continue after key pressed");
+    app.add_flag("-c,--continue", continueRun,
+                 "Whether or not to continue after key pressed");
 
     /* Parse input parameter */
     try