docs: improve analyze guide

[ematipico]

Summary

Adds more information in the contribution guidelines.

I added:

• what's a nursery group
• some tips on how developers should write rules
• explanation of declare_node_union
• code tips around the try operator and let else

I moved the sections around, in order to create a flow that made sense:

• concepts
• coding
  • macros
  • semantic model
  • etc.
• testing
• documentation
• codegen
• commit

Before, it didn't make sense.

Test Plan

Proofread.

Here's the rendered file, the code diff doesn't help.

[Conaclos]

Much better! I left some fixes and suggestions.

[Conaclos]

Should we add some words about fix_kind and sources?

[ematipico]

I'll do it in a second Pr

[Sec-ant]

And a line that is not edited:

biome/crates/biome_analyze/CONTRIBUTING.md

Line 25 in ea6ed8d

_Biome_ follows a naming convention according to what the rule do:

according to what the rule do: => according to what the rule does:

[codspeed-hq]

CodSpeed Performance Report

Merging #2910 will not alter performance

_{Comparing docs/more-info (5dbd55f) with main (2226bae)}

Summary

✅ 87 untouched benchmarks

🆕 5 new benchmarks
⁉️ 12 (👁 12) dropped benchmarks

Benchmarks breakdown

	Benchmark	main	docs/more-info	Change
🆕	json_formatter[big5-added.json]	N/A	8.9 ms	N/A
🆕	json_formatter[canada.json]	N/A	3.8 s	N/A
👁	json_formatter[compiler.js]	2.9 s	N/A	N/A
👁	json_formatter[d3.min.js]	2.3 s	N/A	N/A
🆕	json_formatter[db.json]	N/A	257.8 ms	N/A
👁	json_formatter[dojo.js]	158.9 ms	N/A	N/A
🆕	json_formatter[eucjp.json]	N/A	16.8 ms	N/A
👁	json_formatter[jquery.min.js]	665 ms	N/A	N/A
👁	json_formatter[math.js]	4.7 s	N/A	N/A
🆕	json_formatter[package-lock.json]	N/A	114.2 ms	N/A
👁	json_formatter[pixi.min.js]	2.6 s	N/A	N/A
👁	json_formatter[react-dom.production.min.js]	789.7 ms	N/A	N/A
👁	json_formatter[react.production.min.js]	40.4 ms	N/A	N/A
👁	json_formatter[tex-chtml-full.js]	5.8 s	N/A	N/A
👁	json_formatter[three.min.js]	3.1 s	N/A	N/A
👁	json_formatter[typescript.js]	18.5 s	N/A	N/A
👁	json_formatter[vue.global.prod.js]	1 s	N/A	N/A