Improve README pages

[alexdewar]

Description

I meant to do this in #1070, but forgot.

As pointed out by @tsmbland, the information provided in docs/README.md is currently a bit sparse (e.g. it doesn't tell users how to install MUSE2), which isn't ideal as it's the first page some users may land on. I've reworked things a bit to provide more information on getting started in docs/README.md. I've removed the information about getting started from the GitHub README.md file and added a link to the docs instead; I think that's a better place for this content.

Type of change

• Bug fix (non-breaking change to fix an issue)
• New feature (non-breaking change to add functionality)
• Refactoring (non-breaking, non-functional change to improve maintainability)
• Optimization (non-breaking change to speed up the code)
• Breaking change (whatever its nature)
• Documentation (improve or add documentation)

Key checklist

• All tests pass: $ cargo test
• The documentation builds and looks OK: $ cargo doc
• Update release notes for the latest release if this PR adds a new feature or fixes a bug
  present in the previous release

Further checks

• Code is commented, particularly in hard-to-understand areas
• Tests added that prove fix is effective or that feature works

[Copilot]

Pull request overview

This pull request reorganizes README documentation to improve the getting started experience for new users. The changes move detailed installation and getting started information from the GitHub README to the documentation README, making the docs more comprehensive while keeping the GitHub README more focused.

Changes:

• Enhanced docs/README.md with detailed getting started information including installation options and links to relevant resources
• Simplified README.md to provide a high-level overview and direct users to the documentation for getting started details
• Moved the warning about MUSE2's current limitations to a more prominent location in both READMEs

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 1 comment.

File	Description
docs/README.md	Expanded with comprehensive getting started section including installation instructions, development setup, and links to user/developer guides
README.md	Streamlined to remove detailed getting started instructions and redirect users to documentation; reorganized overview section

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[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 82.09%. Comparing base (5ddf353) to head (9711b3b).
⚠️ Report is 1 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #1074   +/-   ##
=======================================
  Coverage   82.09%   82.09%           
=======================================
  Files          53       53           
  Lines        7310     7310           
  Branches     7310     7310           
=======================================
  Hits         6001     6001           
  Misses       1019     1019           
  Partials      290      290           

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