docs: fix markdownlint warnings and refine documentation files

[renan-cm-apolo]

Description

This PR fixes Markdown formatting errors, lint warnings, and inconsistencies across Luma's documentation files.

Changes

Fixed markdownlint warnings and formatting issues, including:

• Corrected heading hierarchy and list item prefixes (MD029)
• Fixed unlabelled code blocks and dangling URLs
• Cleaned up trailing whitespace and list spacing
• Updated build, installation, and testing command instructions
• Corrected paths and setup instructions for Windows, Linux, and macOS
• Removed outdated references (generics, LLVM, Meson, Ninja)
• Fixed typos and improved grammar across docs
• Refined release notes for v0.3.4 and v0.3.5, and synced TODO with implemented features

Validation

• Verified zero diagnostic/lint errors across revised .md files in VS Code
• Executed git diff --check with no whitespace or formatting errors
• Checked and balanced all Markdown code blocks

[TheDevConnor]

LGTM. Thank you for going through and fixing my spelling mistakes as well!

[renan-cm-apolo]

You're welcome! Happy to help clean things up. I'm looking forward to contributing more to Luma soon!