Add changelog entry and README link for subagent example (#215)

AGENTS.md

@@ -49,7 +49,7 @@ When closing issues via commit:
 - Technical prose only, be kind but direct (e.g., "Thanks @user" not "Thanks so much @user!")
 
 ## Changelog
-Location: `packages/coding-agent/CHANGELOG.md`
+Location: `packages/coding-agent/CHANGELOG.md`, `packages/ai/CHANGELOG.md`, `packages/tui/CHANGELOG.md`, pick the one relevant to the changes or ask user.
 - New entries ALWAYS go under `## [Unreleased]` section
 - NEVER modify already-released version sections (e.g., `## [0.12.2]`)
 - Each version section is immutable once released

packages/coding-agent/CHANGELOG.md

@@ -2,6 +2,10 @@
 
 ## [Unreleased]
 
+### Added
+
+- **Subagent orchestration example**: Added comprehensive custom tool example for spawning and orchestrating sub-agents with isolated context windows. Includes scout/planner/reviewer/worker agents and workflow commands for multi-agent pipelines. ([#215](https://github.com/badlogic/pi-mono/pull/215) by [@nicobailon](https://github.com/nicobailon))
+
 ### Breaking Changes
 
 - **Hook `tool_result` event restructured**: The `ToolResultEvent` now exposes full tool result data instead of just text. ([#233](https://github.com/badlogic/pi-mono/pull/233))

packages/coding-agent/README.md

@@ -843,7 +843,7 @@ Pi is opinionated about what it won't do. These are intentional design decisions
 
 **No MCP.** Build CLI tools with READMEs (see [Skills](#skills)). The agent reads them on demand. [Would you like to know more?](https://mariozechner.at/posts/2025-11-02-what-if-you-dont-need-mcp/)
 
-**No sub-agents.** Spawn pi instances via tmux, or build a task tool with [custom tools](#custom-tools). Full observability and steerability.
+**No sub-agents.** Spawn pi instances via tmux, or [build your own sub-agent tool](examples/custom-tools/subagent/) with [custom tools](#custom-tools). Full observability and steerability.
 
 **No permission popups.** Security theater. Run in a container or build your own with [Hooks](#hooks).