[Enh]: Allow setting OpenAPI description via configuration

[cbunyard]

Is your feature request related to a problem? Please describe.
I would like to provide a custom description in the OpenAPI output for my API, so that client developers and documentation tools see a meaningful summary of the API's purpose.

Describe the solution you'd like
Add a new property (e.g., openapi-description) under the runtime section of the config file. This value should be used as the description field in the OpenAPI info object.

Describe alternatives you've considered
There is currently no way to set this value; the description is missing or hardcoded.

Additional context
Example config:
"runtime": { "openapi-description": "This API provides access to the company database. Use these endpoints to query and manage data.", ... }

Expected OpenAPI output:
"info": { "title": "Data API builder - REST Endpoint", "version": "1.0.0", "description": "This API provides access to the company database. Use these endpoints to query and manage data." }