NGINX example of stripping count headers

[begriffs]

Fill in the missing example in https://postgrest.com/en/v0.4/admin.html#count-header-dos

[steve-chavez]

We can probably make this how-to a bit more generic and also show how to add headers and read them in PostgREST.

Like passing the complete url through a header or an X-Request-Id using nginx $request_id.

I think now that trying to make these generic is a bad idea. Of course, how-tos should be focused and then the user can extrapolate to other use cases.

[steve-chavez]

Btw, I'll delete the placeholder Nginx snippet in http://postgrest.org/en/v5.2/admin.html#count-header-dos. Looks a bit sloppy for official docs.

[steve-chavez]

Seems this can be done with a combination of https://serverfault.com/a/360151/468864 and https://stackoverflow.com/a/44537739/4692662.

Another choice is doing it with openresty https://stackoverflow.com/a/53086188/4692662. But I think we should stick to plain Nginx where possible.

[wolfgangwalther]

Superseded by PostgREST/postgrest#2987