docs: add v1.0.36-1.0.39 CLI updates to configuration basics (#1563)

- Add shell completion section: copilot completion <bash|zsh|fish>
  subcommand for static shell tab-completion scripts (v1.0.37)
- Add warning that ~/.claude/ agents/skills/commands are no longer
  loaded by Copilot CLI; point to ~/.agents/ as the correct location (v1.0.36)
- Document ctrl+x → b keyboard shortcut for backgrounding running
  tasks (v1.0.39)

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: 2026-04-28
+lastUpdated: 2026-04-29
 estimatedReadingTime: '10 minutes'
 tags:
   - configuration
@@ -402,6 +402,8 @@ In addition to the main config file, GitHub Copilot CLI reads two optional per-p
 
 These files follow the same format as `config.json` and are loaded after the global config, so they can tailor CLI behaviour—including hook definitions—per repository without touching `.github/`.
 
+> **Important (v1.0.36+)**: Custom agents, skills, and commands placed in `~/.claude/` (the Claude Code user directory) are **no longer loaded** by GitHub Copilot CLI. Only `~/.claude/settings.json` is read for configuration. If you previously stored personal agents or skills in `~/.claude/`, move them to the supported locations: `~/.agents/` for user-level agents, `~/.agents/skills/` for personal skills, or `.github/agents/` and `.github/skills/` in your repositories for project-level customizations.
+
 ### Model Picker
 
 The model picker opens in a **full-screen view** with inline reasoning effort adjustment. Use the **← / →** arrow keys to change the reasoning effort level (`low`, `medium`, `high`) directly from the picker without leaving the session. The current reasoning effort level is also displayed in the model header (e.g., `claude-sonnet-4.6 (high)`) so you always know which level is active.
@@ -479,6 +481,8 @@ The exported file contains everything needed to view the session without a netwo
 
 **Keyboard shortcuts for queuing messages**: Use **Ctrl+Q** or **Ctrl+Enter** to queue a message (send it while the agent is still working). **Ctrl+D** no longer queues messages — it now has its default terminal behavior. If you have muscle memory for Ctrl+D queuing, switch to Ctrl+Q.
 
+**Background running tasks**: Press **Ctrl+X → B** to move the current running task or shell command to the background. The task continues executing while you can type a new message or review earlier output. This is useful for long-running commands where you want to interact with the agent while waiting for the result.
+
 The `/ask` command lets you ask a quick question without affecting your conversation history. The current session context is preserved, so you can use it for one-off lookups without derailing an ongoing task. Responses are rendered as full markdown, including tables and formatted links:
 
 ```
@@ -535,6 +539,30 @@ copilot --plan          # start in plan mode (propose without executing)
 
 This is useful in scripts or CI pipelines where you want the CLI to immediately begin working in a specific mode without an interactive prompt.
 
+### Shell Completion
+
+The `copilot completion` subcommand generates a static shell completion script for subcommands, flags, and known option values. Once installed, pressing Tab auto-completes Copilot CLI commands in your terminal.
+
+```bash
+# Bash — add to ~/.bashrc
+eval "$(copilot completion bash)"
+
+# Zsh — add to ~/.zshrc
+eval "$(copilot completion zsh)"
+
+# Fish — add to ~/.config/fish/config.fish
+copilot completion fish | source
+```
+
+Or write the script to a file and source it from your shell profile:
+
+```bash
+copilot completion bash > ~/.copilot-completion.bash
+echo 'source ~/.copilot-completion.bash' >> ~/.bashrc
+```
+
+> **Tip**: Reload your shell (`source ~/.bashrc` or open a new terminal) after adding the completion script for changes to take effect.
+
 ## Common Questions
 
 **Q: How do I disable Copilot for specific files?**