Basic refactor of agile section

[TessFerrandez]

What is done

• Cleaning up structure, to flatten the folder structure
• Fixing links
• Moving content around to where it fits better to avoid readers having to look at multiple docs to get the data

What is not done

Full overview of the content, this is merely a first standardization refactoring to delete superfluous pages and tables of content as the GitHub pages already has nice functionality for automatic TOCs and navigation

[github-actions]

🦙 MegaLinter status: ⚠️ WARNING

Descriptor	Linter	Files	Fixed	Errors	Elapsed time
✅ MARKDOWN	markdownlint	17		0	0.99s
⚠️ MARKDOWN	markdown-table-formatter	17		1	0.29s
✅ MDLINKCHECK	linkcheck	17		0	7.27s
✅ SPELL	cspell	18		0	2.67s

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[Doommius]

Looks good! I really like the more compacted view instead of having many small pages with very little information.

[nyouens]

This is a great contribution Tess, thank you!