docs: fix README timeout defaults and add http_delete body param

[bookingminds]

What kind of change does this PR introduce?

Docs update. The README's published function signatures do not match the shipped functions.

What is the current behavior?

The README documents timeout_milliseconds int default 1000 for net.http_get and net.http_post, and default 2000 for net.http_delete. It also shows net.http_delete without a body parameter.

What is the new behavior?

All three signatures show timeout_milliseconds int default 5000, and net.http_delete includes its body parameter, matching sql/pg_net.sql on master:

create or replace function net.http_delete(
url text,
params jsonb default '{}'::jsonb,
headers jsonb default '{}'::jsonb,
timeout_milliseconds int default 5000,
body jsonb default null
)

Additional context

The same two errors, with a different wrong timeout value, appear in the Supabase docs guide for pg_net. I opened a separate PR for that page.

[utkarash2991]

hey @bookingminds I took the liberty of fixing the minor comment on the Pr. Hope thats ok . Rest all looks good to me. Going ahead with the merge.

[bookingminds]

Thanks for catching that and for fixing it yourself rather than bouncing
it back the closing fence was collateral from editing in the GitHub web
editor, and I should have re-read the rendered diff before pushing. I clone
and diff locally now. Appreciated.