PS4M example for local setup

[olexandr-havryliak]

This pull request introduces a complete local development stack for Percona Search for MongoDB (PS4M), using Docker Compose. It provides a single-node replica set of Percona Server for MongoDB (mongod) and a mongot service for search functionality, along with all necessary configuration, secrets, and a comprehensive README with usage instructions and examples.

The most important changes are:

Docker Compose Stack and Service Initialization

• Added docker-compose.yml to define mongod and mongot services, including initialization logic for replica set, user creation, health checks, and service dependencies. Data is persisted in Docker volumes.

Configuration and Secrets

• Added config/mongod.conf and config/mongot.yml for service configuration, enabling authentication, replica set, gRPC search, and proper service wiring. [1] [2]
• Added a shared config/keyfile for internal authentication between services.

Documentation and Usage Examples

• Added a detailed README.md explaining prerequisites, setup, connection instructions, and troubleshooting. Includes step-by-step examples for full-text and vector search, with ready-to-run mongosh snippets.

These changes together provide a ready-to-use local environment for experimenting with Percona Search for MongoDB, including both text and vector search capabilities.