#3 add changes to the README file

README.md

-# Cache
+# Cache service
 
-Cache exposes HTTP interface for working with Redis. 
\ No newline at end of file
+Cache service exposes HTTP interface for working with Redis.
+
+### Basic Architecture
+
+```mermaid
+flowchart LR
+   A[Client] -- request --> B[Cache Service] --> C[(Redis)]
+```
+
+### API Documentation
+
+The API Documentation is accessible at `/swagger-ui` path in OAS 3.0 format.
+Example: `localhost:8080/swagger-ui`
+
+### Prerequisites
+
+There must be a running instance of [Redis](https://redis.io/) visible to the service.
+The address, username and password of the Redis in-memory store instance must be provided as environment variables.
+
+Example:
+```
+REDIS_ADDR="localhost:6379"
+REDIS_USER="user"
+REDIS_PASS="pass"
+```
+
+### Development
+
+This service uses [Goa framework](https://goa.design/) v3 as a backbone. [This](https://goa.design/learn/getting-started/) is a good starting point for learning to use the framework.
+
+### Dependencies and Vendor
+
+The project uses Go modules for managing dependencies and we commit the `vendor` directory.
+When you add/change dependencies, be sure to clean and update the `vendor` directory before
+submitting your Merge Request for review.
+```shell
+go mod tidy
+go mod vendor
+```
+
+### Tests and Linters
+
+To execute the units tests for the service go to the root project directory and run:
+```go
+go test -race ./...
+```
+
+To run the linters go to the root project directory and run:
+```go
+golangci-lint run
+```