Mention custom_selector for Coupled component updates bullet

Author: andressrg

docs/docs/api/optimizers/GEPA.md

@@ -124,7 +124,7 @@ Consider implementing a custom instruction proposer when you need:
 - **Nuanced control on limits and length constraints**: Have more fine-grained control over instruction length, format, and structural requirements
 - **Domain-specific information**: Inject specialized knowledge, terminology, or context that the default proposer lacks and cannot be provided via feedback_func. This is an advanced feature, and most users should not need to use this.
 - **Provider-specific prompting guides**: Optimize instructions for specific LLM providers (OpenAI, Anthropic, etc.) with their unique formatting preferences
-- **Coupled component updates**: Handle situations where 2 or more components need to be updated together in a coordinated manner, rather than optimizing each component independently
+- **Coupled component updates**: Handle situations where 2 or more components need to be updated together in a coordinated manner, rather than optimizing each component independently (refer to component_selector parameter, in Custom Component Selection section, for related functionality)
 - **External knowledge integration**: Connect to databases, APIs, or knowledge bases during instruction generation
 
 ### Available Options