Update README.md

[eldiaz00]

Add screenshot to README

Description

Fixes # (issue)

Screenshots (if appropriate):

Type of change

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)
• This change requires a documentation update
• [ c ] Housekeeping

How Has This Been Tested?

Visually

Test Configuration:

• Operating system: <Name, version number>
• Graphics Card: <Manufacturer (likely Intel, NVidia, AMD?), Model (HD, Geforce, Radeon..., with model number), driver version?>

Checklist:

[github-actions]

Thanks for adding your first pull request to Stellarium. If you have questions, please do not hesitate to contact us.

[gzotti]

If we add a screenshot, it should be from 2024, not 2013.

[10110111]

Also, it should use the nicest graphics available, i.e. with ShowMySky atmosphere and multisampling enabled, and the lossy compression should be much less aggressive.