Improve numerical readability scores of our README

[samcunliffe]

Following on from #546, I've reworded our README, using vale's Readability suite.
I don't think there's a nice way to get vale to make a comparison of values between two commits (@paddyroddy?), so here's a manual comparison table (which I hope is helpful, because it was very boring to make!)

Advice	Before (1ddd9b8)		After (c212066)
Keep the Flesch reading ease score above 70.	56.42	🔴	64.17	🔴
Try to keep the LIX score below 35.	43.12	🔴	39.78	🔴
Try to keep the Coleman–Liau Index grade below 9.	10.19	🔴	9.20	🔴
Try to keep the Flesch–Kincaid grade level below 8.	9.10	🔴	< 8	✅
Try to keep the SMOG grade below 10.	11.10	🔴	< 10	✅
Try to keep the Automated Readability Index below 8.	8.45	🔴	< 8	✅
Try to keep the Gunning-Fog index below 10.	10.20	🔴	< 10	✅

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You can check these yourself with:

cd /place/where/this/repo/is
vale sync
vale README.md

[Copilot]

Pull Request Overview

This PR improves the numerical readability scores of the README by simplifying language and restructuring content. The changes aim to make the documentation more accessible while maintaining all essential information.

Key changes:

• Simplified language and shortened sentences throughout the README
• Restructured sections with clearer headings and better organization
• Added a dedicated "Need help?" section for support information

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[paddyroddy]

I don't think there's a nice way to get vale to make a comparison of values between two commits

I highly doubt it. We could do it in our own way fairly easily, but vale isn't centred around the Readability rule.

[paddyroddy]

Some thoughts

[samcunliffe]

Cheers, Paddy! I've re-requested a review from @UCL-ARC/collaborations-python-tooling to get a second.

@matt-graham and @dstansby, you both wrote earlier versions of this, so your opinions are gratefully received. (If you have the capacity to review...)

[samcunliffe]

I will update this. It's been ages but still feels worthwhile.

[matt-graham]

This all looks great to me, thanks @samcunliffe for picking this up again.

[paddyroddy]

👌