[office-js, office-js-preview] Add note that Office.isSetSupported doesn't work (DefinitelyTyped#73990)

Author: AlexJerabek

types/office-js-preview/index.d.ts

@@ -288,6 +288,8 @@ declare namespace Office {
      */
     function initialize(reason: InitializationReason): void;
     /**
+     * **WARNING**: This API returns inaccurate values when used on desktop applications. Use `Office.context.requirements.isSetSupported` instead.
+     * 
      * Checks if the specified requirement set is supported by the Office application.
      * @param name - Set name; e.g., "MatrixBindings".
      * @param minVersion - The minimum required version; e.g., "1.4".

types/office-js/index.d.ts

@@ -288,6 +288,8 @@ declare namespace Office {
      */
     function initialize(reason: InitializationReason): void;
     /**
+     * **WARNING**: This API returns inaccurate values when used on desktop applications. Use `Office.context.requirements.isSetSupported` instead.
+     * 
      * Checks if the specified requirement set is supported by the Office application.
      * @param name - Set name; e.g., "MatrixBindings".
      * @param minVersion - The minimum required version; e.g., "1.4".