Documentation Improvements for 3.x

[ddtmachado]

Welcome!

• Yes, I've searched similar issues on GitHub and didn't find any.
• Yes, I've searched similar issues on the Traefik community forum and didn't find any.

What did you expect to see?

This proposal aims to highlight the direction we want to take on the documentation for the next major release, by expanding it in key areas while also removing or reworking sections where it makes sense.

The guidelines might change, as we try and fail/succeed, so make sure you check them again before working on a doc.

Guidelines

Be more Kubernetes centric
Based on anonymous usage data it's clear that Kubernetes is already the main provider in use, so it makes sense to shift the documentation to use Kubernetes examples first whenever it fits.

Guides should feel like a journey and not like a reference
Whenever we add a guide it should feel more like a journey “From zero to Hero” and less like a “how to” install another tool. As an example the “Getting Started” guide should cover the basics on routing, certificate management, observability and so on.

Configuration examples should work out of the box
When adding a configuration snippet it should work by just copying and pasting, if that is not possible a description on how to customize it properly should follow.

Prefer grouping configuration keys when adding snippets
Rather than showing one example on each individual property of a configuration object, prefer to group everything in the same table like this example.

Emphasize the version selector
#9854

Improve Headers middleware documentation
#9859 (comment)

Proposals

• Rework the "Kubernetes and Let's Encrypt Guide" #9548
• Replace mkdocs theme fork by the original mkdocs with shared web components #9567
• Have a dedicated documentation page/section for the "default" resources mechanism (TLSOptions, TLSStore, ServersTransport...) #9637

[rtribotte]

Because of the removal of the default serversTransport from the static configuration (#9528), which is replaced by the dynamic configuration default mechanism (as for the tlsOptions), I think it would make sense to have a dedicated part of the documentation that explains how works the "default resource mechanism" in Traefik.

See #9637.

[svx]

#9920