fix(README): Correct configuration lines in link

[kunzaatko]

• Use the main and HEAD for the snippet in README for the configuration.
• Added a note for developer, that if the configuration changes, he/she
  should update the README link line numbers

Reason: It can be quite counterintuitive to setup the configuration that
is not up to date such that something from the copied configuration is
already deprecated. It should also adhere to the new provider format,
so that users know what to use.

[Robitx]

@kunzaatko yep, I've forgot to update the link, thanks for the reminder. 👍

The trouble is that the "markdown code reference snippet" doesn't work without a static commit hash (with main it just becomes a normal link) and the line numbers would still need update with every significant conf change.

This looks like a candidate for some CI function, which will keep the README reference updated.

[kunzaatko]

Didn't know that... That is quite annoying, since you would usually want to update the documentation in the same commit as the changes to the config. I will try to look into the CI possibility. Right now, I will change it to the static link, right?

[Robitx]

I've updated the reference directly, we can keep this PR around if you want to look into the CI options for solving it.

[Robitx]

Context https://docs.github.com/en/get-started/writing-on-github/working-with-advanced-formatting/creating-a-permanent-link-to-a-code-snippet

[Robitx]

@kunzaatko I haven't found existing solution for this, so created my own github action https://github.com/Robitx/snippet-permalink-updater-action

e87d1ec ✔️

[kunzaatko]

Great work! Thank you!