Add README Generation to Lambda CLI

[nourshoreibah]

User Story

As a developer, I want lambda CLI to automatically generate READMEs for each lambda

Description

Currently, each lambda service is pretty much undocumented. Similar to how we generate READMEs for Terraform modules, we need the lambda CLI to automatically generate a README.md file for each lambda that documents its endpoints and local setup instructions

This ticket is to enhance the lambda CLI tool to generate standardized README files when creating or updating lambda services.

Acceptance criteria

• Update apps/backend/lambdas/tools/lambda-cli.js to generate README.md when creating a lambda
• README includes: lambda name, description, available endpoints, setup instructions
• Add a generate-readme command to regenerate READMEs for existing lambdas
• Test by creating a new lambda and verifying README is generated
• Regenerate READMEs for existing lambdas
  BONUS: Make a GHA workflow that generates/edits them!