Add Git-Galaxy-Finder to GitHub browser extensions

[slmkhanahmed]

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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Editing an existing topic or collection

I'm suggesting these edits to an existing topic or collection:

• Image (and my file is *.png, square, dimensions 288x288, size <= 75 kB)
• Content (and my changes are in index.md)

I am adding a relevant browser extension to this collection. I noticed other similar GitHub-related tools and extensions are already listed here, and this addition provides further value to users looking for ways to enhance their GitHub workflow.

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[ahpook]

This needs to be at the end of the list, not the start- please fix!