Update Documentation for Customizing the solution (CustomizeSolution.md)

[rishabhmonga119]

Motivation

The document to customize the solution is outdated. The file names and methods have been renamed, causing confusing to follow the documentation.

Examples

• no file named messages.py or utils.
• agents module has been renamed to kernel_agents
• ..

[Vamshi-Microsoft]

Hi @rishabhmonga119 Thanks for reporting this Issue, we will look into this Issue and get back to you. Sorry for the inconvenience.