Discovery landing page (#58174)

Co-authored-by: Claire W <78226508+crwaters16@users.noreply.github.com>
Co-authored-by: Anne-Marie <102995847+am-stead@users.noreply.github.com>
Co-authored-by: Jules <19994093+jules-p@users.noreply.github.com>
Co-authored-by: Jules Porter <jules-p@users.noreply.github.com>
Co-authored-by: hubwriter <hubwriter@github.com>
Co-authored-by: Robert Sese <734194+rsese@users.noreply.github.com>

content/copilot/concepts/completions/code-referencing.md

@@ -9,6 +9,8 @@ topics:
 versions:
   feature: copilot
 contentType: concepts
+category: 
+  - Learn about Copilot
 ---
 
 {% jetbrains %}

content/copilot/concepts/completions/code-suggestions.md

@@ -9,6 +9,8 @@ defaultTool: vscode
 topics:
   - Copilot
 contentType: concepts
+category: 
+  - Learn about Copilot
 ---
 
 {% vscode %}

content/copilot/concepts/completions/text-completion.md

@@ -9,6 +9,8 @@ permissions: 'Members of an enterprise with a subscription to [{% data variables
 topics:
   - Copilot
 contentType: concepts
+category: 
+  - Learn about Copilot
 ---
 
 {% data reusables.copilot.text-completion-preview %}