docs(agents): move Goose to YAML Format section in Command File Formats

Goose uses YAML recipes, not Markdown. Remove it from the Markdown Format
list and add a dedicated YAML Format subsection with a representative
recipe example showing prompt: | and {{args}} placeholders.

Author: furkankoykiran

AGENTS.md

@@ -355,7 +355,7 @@ Work within integrated development environments:
 
 ### Markdown Format
 
-Used by: Claude, Cursor, GitHub Copilot, opencode, Windsurf, Junie, Kiro CLI, Amp, SHAI, IBM Bob, Kimi Code, Qwen, Pi, Codex, Auggie, CodeBuddy, Qoder, Roo Code, Kilo Code, Trae, Antigravity, Mistral Vibe, iFlow, Forge, Goose
+Used by: Claude, Cursor, GitHub Copilot, opencode, Windsurf, Junie, Kiro CLI, Amp, SHAI, IBM Bob, Kimi Code, Qwen, Pi, Codex, Auggie, CodeBuddy, Qoder, Roo Code, Kilo Code, Trae, Antigravity, Mistral Vibe, iFlow, Forge
 
 **Standard format:**
 
@@ -390,6 +390,25 @@ Command content with {SCRIPT} and {{args}} placeholders.
 """
 ```
 
+### YAML Format
+
+Used by: Goose
+
+```yaml
+version: 1.0.0
+title: "Command Title"
+description: "Command description"
+author:
+  contact: spec-kit
+extensions:
+  - type: builtin
+    name: developer
+activities:
+  - Spec-Driven Development
+prompt: |
+  Command content with {SCRIPT} and {{args}} placeholders.
+```
+
 ## Directory Conventions
 
 - **CLI agents**: Usually `.<agent-name>/commands/`