P0 follow-up for EA-471. Updates plugin-dev teaching materials to stop
recommending the commands/ directory layout for new plugins:
- command-development/SKILL.md: add legacy banner at top pointing to
skills/ format
- create-plugin.md: update scaffolding to create skills/<name>/SKILL.md
instead of commands/; mark commands/ as acceptable legacy alternative;
update all examples, tables, and testing instructions
- example-plugin: migrate example-command to skills/example-command/SKILL.md;
keep commands/example-command.md with a legacy-format note; update README
to reflect new preferred structure
Both formats remain loaded identically — this is a documentation change only.
Refs: anthropics/apps#26827
Skills and commands are now merged, so SKILL.md name fields surface
in the UI as slash commands. Upper Space names like 'Hook Development'
become '/Hook Development', which doesn't work since user-invoked
commands don't support spaces.
Rename all affected SKILL.md name fields to lower-kebab-case:
- hookify: Writing Hookify Rules -> writing-hookify-rules
- plugin-dev: Agent Development -> agent-development
- plugin-dev: Command Development -> command-development
- plugin-dev: Hook Development -> hook-development
- plugin-dev: MCP Integration -> mcp-integration
- plugin-dev: Plugin Settings -> plugin-settings
- plugin-dev: Plugin Structure -> plugin-structure
- plugin-dev: Skill Development -> skill-development
Also update references in plugin-dev/README.md.
