Add GitHub Copilot app learning hub page (#1981)

* Add GitHub Copilot app learning hub page

- Create new learning hub page covering Copilot app basics, features, and use cases
- Include information about target audiences (developers, non-dev roles, teams with parallel work)
- Highlight key features: My Work view, isolated worktrees, canvases, Agent Merge
- Add installation and getting started instructions
- Update learning hub index to include app in Getting Started section

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

* Refine GitHub Copilot app learning hub page

- Add the app to the learning hub navigation
- Tighten the page copy around audiences, features, and getting started
- Keep canvases and automations high level as requested

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

* Potential fix for pull request finding

Co-authored-by: Copilot Autofix powered by AI <175728472+Copilot@users.noreply.github.com>

* Potential fix for pull request finding

Co-authored-by: Copilot Autofix powered by AI <175728472+Copilot@users.noreply.github.com>

---------

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
Co-authored-by: Copilot Autofix powered by AI <175728472+Copilot@users.noreply.github.com>

website/astro.config.mjs

@@ -62,30 +62,19 @@ export default defineConfig({
           },
         },
       ],
-      customCss: ["./src/styles/starlight-overrides.css", "./src/styles/global.css"],
+      customCss: [
+        "./src/styles/starlight-overrides.css",
+        "./src/styles/global.css",
+      ],
       editLink: {
         baseUrl:
           "https://github.com/github/awesome-copilot/edit/staged/website/",
       },
       sidebar: [
-        {
-          label: "Browse Resources",
-          items: [
-            { label: "Home", link: "/" },
-            { label: "Agents", link: "/agents/" },
-            { label: "Instructions", link: "/instructions/" },
-            { label: "Skills", link: "/skills/" },
-            { label: "Hooks", link: "/hooks/" },
-            { label: "Workflows", link: "/workflows/" },
-            { label: "Canvas Extensions", link: "/extensions/" },
-            { label: "Plugins", link: "/plugins/" },
-            { label: "Tools", link: "/tools/" },
-            { label: "Contributors", link: "/contributors/" },
-          ],
-        },
         {
           label: "Fundamentals",
           items: [
+            "learning-hub/github-copilot-app",
             "learning-hub/what-are-agents-skills-instructions",
             "learning-hub/agents-and-subagents",
             "learning-hub/understanding-copilot-context",
@@ -131,6 +120,21 @@ export default defineConfig({
             },
           ],
         },
+        {
+          label: "Browse Resources",
+          items: [
+            { label: "Home", link: "/" },
+            { label: "Agents", link: "/agents/" },
+            { label: "Instructions", link: "/instructions/" },
+            { label: "Skills", link: "/skills/" },
+            { label: "Hooks", link: "/hooks/" },
+            { label: "Workflows", link: "/workflows/" },
+            { label: "Canvas Extensions", link: "/extensions/" },
+            { label: "Plugins", link: "/plugins/" },
+            { label: "Tools", link: "/tools/" },
+            { label: "Contributors", link: "/contributors/" },
+          ],
+        },
       ],
       disable404Route: true,
       // pagefind: true is required so Starlight renders the search UI.