Leave relevant note on default gui size macros

Signed-off-by: falkTX <falktx@falktx.com>

distrho/DistrhoInfo.hpp

@@ -628,6 +628,8 @@ START_NAMESPACE_DISTRHO
    Setting this macro allows to skip a temporary UI from being created in certain VST2 and VST3 hosts.
    (which would normally be done for knowing the UI size before host creates a window for it)
 
+   Value must match 1x scale factor.
+
    When this macro is defined, the companion DISTRHO_UI_DEFAULT_HEIGHT macro must be defined as well.
  */
 #define DISTRHO_UI_DEFAULT_WIDTH 300
@@ -637,6 +639,8 @@ START_NAMESPACE_DISTRHO
    Setting this macro allows to skip a temporary UI from being created in certain VST2 and VST3 hosts.
    (which would normally be done for knowing the UI size before host creates a window for it)
 
+   Value must match 1x scale factor.
+
    When this macro is defined, the companion DISTRHO_UI_DEFAULT_WIDTH macro must be defined as well.
  */
 #define DISTRHO_UI_DEFAULT_HEIGHT 300