Product file editor: Document bundleUrlTypes support on macOS

Follow-up on #1326.
Contributes to eclipse-platform/eclipse.platform.ui#1901.

org.eclipse.pde.doc.user/guide/tools/editors/product_editor/launching.htm

@@ -23,6 +23,7 @@ <h2>Program Launcher</h2>
 <p><img src="../../../images/product_editor/launcher_program.png" alt="Launcher Exe" ></p>
 <p>To customize the name of the launcher, just enter the name in the <strong>Launcher Name</strong> field. If left unspecifed, the name will default to <em>eclipse</em>.</p>
 <p>Customizing the launcher icon varies per platform. The product editor indicates the platform requirements, and flags warnings at the top of the page if the supplied icons do not match the size or depth requirements. </p>
+<p>On macOS it is also possible to configure URL schemes to be handled by the native launcher. This information is placed as <a href="https://developer.apple.com/documentation/bundleresources/information_property_list/cfbundleurltypes">CFBundleURLTypes</a> entries in the <em>Info.plist</em> file of the app bundle. A corresponding <code>org.eclipse.urischeme.uriSchemeHandlers</code> extension point implementation should then be contributed by one of the plug-ins in the product.</p>
 
 <h2>Launching Arguments</h2>
 <p>The <strong>Launching Arguments</strong> section lets you specify the program and VM arguments that should be used for your product. These arguments are stored in a file named <em>&lt;launcher_name&gt;.ini </em>at the root of the product. PDE creates this file based on the values entered in this section. You can specify arguments for all Platforms, or choose a tab to specify arguments that apply only to a particular platform. You may use the combo box below the Platform tabs to specify arguments for a specific OS architecture. The <strong>Complete Arguments Preview</strong> text shows you what arguments will be used for the selected Platform and OS architecture, including arguments that apply to all platforms or architectures. </p>