docs(learning-hub): update for Copilot CLI v1.0.64-v1.0.65 features (#2127)

- creating-effective-skills: add 'copilot skill' CLI subcommand for
  listing, adding, and removing skills (v1.0.65); add '/skill' alias
- automating-with-hooks: document userPromptSubmitted additionalContext
  injection into model-facing prompt (v1.0.65); update hook events table
- copilot-configuration-basics: add opt-in CI check status bar indicator
  for current branch (v1.0.65)
- building-custom-agents: add note that /security-review is now available
  to all users without --experimental (v1.0.64)

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/creating-effective-skills.md

@@ -3,7 +3,7 @@ title: 'Creating Effective Skills'
 description: 'Master the art of writing reusable, shareable skill folders that deliver consistent results across your team.'
 authors:
   - GitHub Copilot Learning Hub Team
-lastUpdated: 2026-06-23
+lastUpdated: 2026-06-25
 estimatedReadingTime: '9 minutes'
 tags:
   - skills
@@ -370,6 +370,19 @@ A: Skills can be invoked in several ways:
 - **Multiple skills in one message**: You can invoke multiple skills in a single message (e.g., `/generate-tests and then /conventional-commit`). Both skills will be executed in sequence.
 - **Agent discovery**: Agents can also discover and invoke skills automatically based on the skill's `description` and the user's intent — no slash command required.
 
+**Q: How do I manage skills from the CLI?**
+
+A: The `copilot skill` subcommand (v1.0.65+) lets you list, add, and remove skills directly from the terminal without editing config files manually:
+
+```bash
+copilot skill list                      # list all currently loaded skills
+copilot skill add ./my-skill/           # add a skill from a local directory
+copilot skill add https://example.com/skill.zip  # add a skill from a URL
+copilot skill remove my-skill           # remove an installed skill by name
+```
+
+You can also run `/skill` (or the existing `/skills`) inside an interactive session to see what's loaded. The `copilot skill` subcommand is the recommended way to install skills that aren't packaged inside a plugin.
+
 **Q: How are skills different from prompts?**
 
 A: Skills replace the older prompt file (`*.prompt.md`) format. Skills offer agent discovery (prompts were manual-only), bundled assets (prompts were single files), and cross-platform portability via the Agent Skills specification. If you have existing prompts, consider migrating them to skills.