docs(skill-creator): Enhance frontmatter documentation with $ARGUMENTS and examples

Improvements to the YAML frontmatter documentation merged from PR #6:

- Add explanation of $ARGUMENTS placeholder and how it works with skill invocation
- Add inline example showing /deep-research invocation with arguments
- Expand allowed-tools field with more wildcard examples (npm, docker compose)
- Add hooks field example showing pre-invoke configuration
- Update init_skill.py template with wildcard examples and $ARGUMENTS hint

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

skill-creator/scripts/init_skill.py

@@ -23,8 +23,8 @@ description: [TODO: Complete and informative explanation of what the skill does
 # agent: Explore                   # Subagent type when context: fork (Explore, Plan, general-purpose, or custom)
 # disable-model-invocation: true   # Only allow manual /skill-name invocation, prevent auto-triggering
 # user-invocable: false            # Hide from / menu (for background knowledge only)
-# allowed-tools: Read, Grep        # Tools allowed without permission prompts
-# argument-hint: [filename]        # Autocomplete hint for arguments
+# allowed-tools: Read, Grep, Bash(git *), Bash(npm *)  # Tools allowed without permission prompts (wildcards supported)
+# argument-hint: [filename]        # Autocomplete hint for arguments. Use $ARGUMENTS in content to access user input
 ---
 
 # {skill_title}