docs: update create-plugin command frontmatter to follow best practices

- Shorten description from 96 to 43 characters (under 60 limit)
- Add bracket convention to argument-hint: [plugin-description]
- Restrict Bash tool to mkdir commands: Bash(mkdir:*)

Fixes #99

🤖 Generated with [Claude Code](https://claude.com/claude-code)

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

Author: sjnims

plugins/plugin-dev/commands/create-plugin.md

@@ -1,7 +1,7 @@
 ---
-description: Guided end-to-end plugin creation workflow with component design, implementation, and validation
-argument-hint: Optional plugin description
-allowed-tools: ["Read", "Write", "Edit", "Grep", "Glob", "Bash", "TodoWrite", "AskUserQuestion", "Skill", "Task"]
+description: Create plugins with guided 8-phase workflow
+argument-hint: "[plugin-description]"
+allowed-tools: ["Read", "Write", "Edit", "Grep", "Glob", "Bash(mkdir:*)", "TodoWrite", "AskUserQuestion", "Skill", "Task"]
 ---
 
 # Plugin Creation Workflow