feat: add Evergreen ILS (evergreen-ils) topic with details and logo

[IanSkelskey]

Please confirm this pull request meets the following requirements:

• I followed the contributing guidelines: https://github.com/github/explore/blob/main/CONTRIBUTING.md.
• This change is not self-promotion.

Which change are you proposing?

• Suggesting edits to an existing topic or collection
• Curating a new topic or collection
• Something that does not neatly fit into the binary options above

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Curating a new topic or collection

• I've formatted my changes as a new folder directory, named for the topic or collection as it appears in the URL on GitHub (e.g. https://github.com/topics/[NAME] or https://github.com/collections/[NAME])
• My folder contains a *.png image (if applicable) and index.md
• All required fields in my index.md conform to the Style Guide and API docs: https://github.com/github/explore/tree/main/docs

Many libraries and vendors build Evergreen-adjacent code—deploy scripts, integrations with third‑party services, client libraries, and utilities—across many GitHub orgs. The evergreen-ils topic provides a single, unambiguous tag to group these efforts for better discovery and consistent tagging across the community. After acceptance, I plan to submit a curated collection to highlight core resources and commonly used projects.

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Please note: we will close your PR without comment if you do not check the boxes above and provide ALL requested information.

[Copilot]

Pull Request Overview

This PR adds a new topic for Evergreen ILS, an open source integrated library system. The topic provides discovery and organization for Evergreen-related repositories on GitHub.

• Adds complete topic metadata including aliases, URLs, and related topics
• Includes descriptive content about Evergreen ILS features and community
• References a logo file for the topic

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