docs(learning-hub): document Copilot CLI v1.0.15 new features (#1258)

- Add postToolUseFailure hook event to automating-with-hooks.md:
  clarify that postToolUse now only fires on success, add new event
  to the events table, and add a practical example with migration note
- Add /mcp auth command and device code flow (RFC 8628) to
  understanding-mcp-servers.md authentication section
- Add mcp.config.list/add/update/remove server RPCs section to
  understanding-mcp-servers.md
- Add /share html command to copilot-configuration-basics.md CLI
  Session Commands section
- Update lastUpdated dates to 2026-04-01

Co-authored-by: github-actions[bot] <41898282+github-actions[bot]@users.noreply.github.com>
Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

website/src/content/docs/learning-hub/copilot-configuration-basics.md

@@ -3,7 +3,7 @@ title: 'Copilot Configuration Basics'
 description: 'Learn how to configure GitHub Copilot at user, workspace, and repository levels to optimize your AI-assisted development experience.'
 authors:
   - GitHub Copilot Learning Hub Team
-lastUpdated: 2026-03-30
+lastUpdated: 2026-04-01
 estimatedReadingTime: '10 minutes'
 tags:
   - configuration
@@ -449,6 +449,14 @@ The `/cd` command changes the working directory for the current session. Each se
 
 This is useful when you have multiple backgrounded sessions each focused on a different project directory.
 
+The `/share html` command exports the current session — including conversation history and any research reports — as a **self-contained interactive HTML file**:
+
+```
+/share html
+```
+
+The exported file contains everything needed to view the session without a network connection and can be shared with teammates or stored for later reference. This complements `/share` (which shares via URL) for cases where an offline or attached format is preferred.
+
 The `/allow-all` command (also accessible as `/yolo`) enables autopilot mode, where the agent runs all tools without asking for confirmation. It now supports `on`, `off`, and `show` subcommands:
 
 ```