Document tag replacement in localization docs

[LegendEffects]

Added in https://github.com/laravel/framework/pull/51190

Still not 100% on the wording, especially around the unescaped blade syntax, but gets the basis there.

I'm also not sure on what sort of code styling is best for the example so I've used what StyleCI reformatted the PR to

[taylorotwell]

Drafting until release.

[taylorotwell]

Will try to revisit this a bit later.

[neochief]

FYI, it's still undocumented.

[LegendEffects]

@taylorotwell This is still to be documented but is released as far as I'm aware