Copilot: Move description into markdown file

Change-Id: Ib9f9fec4be31bc60739037883fad02d489303818
Reviewed-by: Alessandro Portale <alessandro.portale@qt.io>

src/plugins/copilot/CMakeLists.txt

@@ -1,5 +1,6 @@
 add_qtc_plugin(Copilot
   PLUGIN_DEPENDS Core LanguageClient
+  LONG_DESCRIPTION_MD Description.md
   SOURCES
     authwidget.cpp authwidget.h
     copilot.qrc

src/plugins/copilot/Copilot.json.in

@@ -16,11 +16,7 @@
                   "Alternatively, this plugin may be used under the terms of the GNU General Public License version 3 as published by the Free Software Foundation with exceptions as appearing in the file LICENSE.GPL3-EXCEPT included in the packaging of this plugin. Please review the following information to ensure the GNU General Public License requirements will be met: https://www.gnu.org/licenses/gpl-3.0.html."
     ],
     "Description" : "View suggestions from GitHub Copilot in code editor.",
-    "LongDescription" : [
-        "You also need:",
-            "- An active GitHub Copilot subscription",
-            "- GitHub Copilot Neovim plugin installed (requires Node.js)"
-    ],
+    "LongDescription" : ${LONG_DESCRIPTION},
     "Url" : "https://www.qt.io",
     "DocumentationUrl" : "https://doc.qt.io/qtcreator/creator-copilot.html",
     ${IDE_PLUGIN_DEPENDENCIES}

src/plugins/copilot/Description.md

@@ -0,0 +1,8 @@
+![Writing a function with Copilot](https://qtccache.qt.io/images/copilot/Copilot.gif)
+
+*Copilot in action*
+
+## You also need:
+
+- An active GitHub Copilot [subscription](https://github.com/features/copilot)
+- GitHub Copilot Neovim plugin [installed](https://github.com/github/copilot.vim?tab=readme-ov-file#getting-started) (requires [Node.js](https://nodejs.org/en/download/package-manager))