Improve marketplace listing

### Describe your use-case which is not covered by existing documentation.

Listing: https://plugins.jetbrains.com/plugin/1885-jenkins-development-support/

- Features on the marketplace, too high level right now
- Add screenshots
- Maybe gif?
- Improve getting started section

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Plugin description is taken from the README.
Most of the rest of it is uploaded directly in the marketplace UI.

All text formatting is done with HTML

Pictures can't have alt+text or captions so any text must be manually overlayed.

### Reference any relevant documentation, other materials or issues/pull requests that can be used for inspiration.

https://plugins.jetbrains.com/docs/marketplace/best-practices-for-listing.html#plugin-description

Look at other listings for inspiration: https://plugins.jetbrains.com/

### Are you interested in contributing to the documentation?

_No response_

Start by comparing the Jenkins Development Support marketplace listing with the plugin README, the linked Marketplace best-practices guide, and other listings for examples. Review the feature descriptions, getting-started section, and available screenshots or GIFs; the listing is done when those areas are more informative and the marketplace presentation is updated consistently.

Written by the indexing model from the issue text.