Move superpowers plugin into plugins/superpowers-bootstrap subdirectory

This restructures the repo to support multiple plugins by moving the current
plugin into a subdirectory. The plugin continues to be published as "superpowers"
in the marketplace.

plugins/superpowers-bootstrap/commands/README.md

@@ -0,0 +1,36 @@
+# Claude Commands
+
+Slash commands for Claude that reference skills.
+
+## Available Commands
+
+- `/brainstorm` - Interactive idea refinement using Socratic method (→ `@skills/collaboration/brainstorming/SKILL.md`)
+- `/write-plan` - Create detailed implementation plan (→ `@skills/collaboration/writing-plans/SKILL.md`)
+- `/execute-plan` - Execute plan in batches with review (→ `@skills/collaboration/executing-plans/SKILL.md`)
+
+## Format
+
+Each command is a simple markdown file containing a single `@` reference to a skill:
+
+```markdown
+@skills/collaboration/brainstorming/SKILL.md
+```
+
+When you run the command (e.g., `/brainstorm`), Claude loads and follows that skill.
+
+## Creating Custom Commands
+
+To add your own commands:
+
+1. Create `your-command.md` in this directory
+2. Add a single line referencing a skill:
+   ```markdown
+   @skills/your-category/your-skill/SKILL.md
+   ```
+3. The command `/your-command` is now available
+
+## Installation
+
+These commands are automatically symlinked to `~/.claude/commands/` by the clank installer.
+
+See `@skills/meta/installing-skills/SKILL.md` for installation details.