docs: improve getting started page structure and readability

[berendt]

Restructure the getting started page for better clarity and scannability:

• Reorganize info box into distinct sections (About, Quick start, Get involved)
• Break long introduction paragraph into shorter, focused paragraphs
• Convert guides list to a table for better overview
• Add bullet points to prerequisites for each technology
• Change final note to tip admonition for better visibility

AI-assisted: Claude Code

[github-actions]

✅MegaLinter analysis: Success

Descriptor	Linter	Files	Fixed	Errors	Warnings	Elapsed time
✅ ACTION	actionlint	3		0	0	0.03s
✅ JSON	jsonlint	4		0	0	0.11s
✅ JSON	prettier	4		0	0	0.42s
✅ JSON	v8r	4		0	0	8.07s
✅ MARKDOWN	markdownlint	159		0	0	1.79s
✅ MARKDOWN	markdown-table-formatter	159		0	0	0.32s
✅ REPOSITORY	checkov	yes		no	no	15.89s
✅ REPOSITORY	git_diff	yes		no	no	0.06s
✅ REPOSITORY	secretlint	yes		no	no	1.56s
✅ REPOSITORY	trufflehog	yes		no	no	4.77s
✅ SPELL	cspell	189		0	0	3.78s
✅ SPELL	lychee	176		0	0	22.57s
✅ YAML	prettier	5		0	0	0.34s
✅ YAML	v8r	5		0	0	6.5s
✅ YAML	yamllint	5		0	0	0.29s

See detailed reports in MegaLinter artifacts

Your project could benefit from a custom flavor, which would allow you to run only the linters you need, and thus improve runtime performances. (Skip this info by defining FLAVOR_SUGGESTIONS: false)

• Documentation: Custom Flavors
• Command: npx mega-linter-runner@9.3.0 --custom-flavor-setup --custom-flavor-linters ACTION_ACTIONLINT,JSON_JSONLINT,JSON_V8R,JSON_PRETTIER,MARKDOWN_MARKDOWNLINT,MARKDOWN_MARKDOWN_TABLE_FORMATTER,REPOSITORY_CHECKOV,REPOSITORY_GIT_DIFF,REPOSITORY_SECRETLINT,REPOSITORY_TRUFFLEHOG,SPELL_CSPELL,SPELL_LYCHEE,YAML_PRETTIER,YAML_YAMLLINT,YAML_V8R