let keybinding for bitrate visibility toggle be customized

doc/keys

@@ -48,6 +48,8 @@
 #
 #key_toggle_mouse = '|'
 #
+#key_toggle_bitrate_visibility = 'B'
+#
 #key_screen_switcher = 9
 #
 #key_help = '1' 265

src/settings.cpp

@@ -516,6 +516,8 @@ void NcmpcppKeys::Read()
 				GetKeys(key, ToggleAddMode);
 			else if (key.find("key_toggle_mouse ") != std::string::npos)
 				GetKeys(key, ToggleMouse);
+			else if (key.find("key_toggle_bitrate_visibility ") != std::string::npos)
+				GetKeys(key, ToggleBitrateVisibility);
 			else if (key.find("key_shuffle ") != std::string::npos)
 				GetKeys(key, Shuffle);
 			else if (key.find("key_toggle_crossfade ") != std::string::npos)