docs: clarify Agent Workspace Build limits for Community deployments (#21961)

## Summary

Updates the AI Governance documentation to explicitly mention that both
Community and Premium deployments include 1,000 Agent Workspace Builds.
Also clarifies that Community deployments do not have access to AI
Bridge or Agent Boundaries.

This is a follow-up to #21943 which made the same clarification in the
Tasks documentation.

## Changes

- Updated the "Agent Workspace Build Limits" section in
`docs/ai-coder/ai-governance.md`
- Added explicit mention that Community deployments lack AI Bridge and
Agent Boundaries access

---

Created on behalf of @mattvollmer

Co-authored-by: blink-so[bot] <211532188+blink-so[bot]@users.noreply.github.com>

docs/ai-coder/ai-governance.md

@@ -131,9 +131,10 @@ may also consume agent workspace builds.
 ### Agent Workspace Build Limits
 
 Without proper controls and sandboxing, it is not recommended to open up Coder
-Tasks to a large audience in the enterprise. Coder Premium deployments include
-1,000 Agent Workspace Builds, primarily for proof-of-concept use and basic
-workflows.
+Tasks to a large audience in the enterprise. Both Community and Premium
+deployments include 1,000 Agent Workspace Builds, primarily for proof-of-concept
+use and basic workflows. Community deployments do not have access to
+[AI Bridge](./ai-bridge/index.md) or [Agent Boundaries](./agent-boundaries/index.md).
 
 Our [AI Governance Add-On](./ai-governance.md) includes a shared usage pool of
 Agent Workspace Builds for automated workflows, along with limits that scale