Update gui readme

[hannaeko]

Purpose

Update the readme to remove outdated information and make it more like other components readme.

Context

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Changes

• Remove some contribution text
• Remove sécurity section because that has not be done for so long
• Remove duplicated acknowledgment to angular cli
• Remove release instructions
• Reorder some sections
• Update the build badge to use github action

How to test this PR

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[hannaeko]

I hope to have addressed all comments.