Enable the provision of a model's description

[dschwartznyc]

Feature Request

Description of Problem

PyPI allows projects to include a one-line description, which is specified in the pyproject.toml file. Currently, the Rune generator does not support this feature, resulting in PyPI project pages displaying "No project description provided" (see issue #4911 in the CDM project).

Proposed Solution

The generator should accept a project description as input and populate the appropriate field in pyproject.toml.

Implementation Options

1. Accept a description file (e.g., description.txt) as input to the generator
2. Accept the description string directly as a generator parameter
3. Include the description as part of the model definition itself
4. Support manual override of the field in pyproject.toml after generation