Add doc comment to settings::autosaveInterval.

include/settings.hpp

@@ -71,6 +71,7 @@ extern bool lockModules;
 extern bool squeezeModules;
 /** Maximum screen redraw frequency in Hz, or 0 for unlimited. */
 extern float frameRateLimit;
+/** Interval between autosaves in seconds. */
 extern float autosaveInterval;
 extern bool skipLoadOnLaunch;
 extern std::list<std::string> recentPatchPaths;