refactor: move help URL into buildconfig

buildconfig/BuildConfig.cpp.in

@@ -50,6 +50,7 @@ Config::Config()
     VERSION_STR = "@Launcher_VERSION_STRING@";
     NEWS_RSS_URL = "@Launcher_NEWS_RSS_URL@";
     NEWS_OPEN_URL = "@Launcher_NEWS_OPEN_URL@";
+    HELP_URL = "@Launcher_HELP_URL@";
     IMGUR_CLIENT_ID = "@Launcher_IMGUR_CLIENT_ID@";
     MSA_CLIENT_ID = "@Launcher_MSA_CLIENT_ID@";
     META_URL = "@Launcher_META_URL@";

buildconfig/BuildConfig.h

@@ -73,6 +73,11 @@ public:
      */
     QString NEWS_OPEN_URL;
 
+    /**
+     * URL (with arg %1 to be substituted with page-id) that gets opened when the user requests help
+     */
+    QString HELP_URL;
+
     /**
      * Client ID you can get from Imgur when you register an application
      */