[OpenSIPS-Devel] [OpenSIPS/opensips] c3f41c: drouting docs: Fix bad use_next_gw() example

[Liviu Chircu]

  Branch: refs/heads/2.4
  Home:   https://github.com/OpenSIPS/opensips
  Commit: c3f41c655077c9b7b99a3df1b326fa5ce47c3633
      https://github.com/OpenSIPS/opensips/commit/c3f41c655077c9b7b99a3df1b326fa5ce47c3633
  Author: Liviu Chircu <liviu at opensips.org>
  Date:   2021-06-03 (Thu, 03 Jun 2021)

  Changed paths:
    M modules/drouting/doc/drouting_admin.xml
    M modules/drouting/drouting.c

  Log Message:
  -----------
  drouting docs: Fix bad use_next_gw() example

The carrier attrs are extracted using the 4th parameter, not the 3rd.
Also fix a variable naming inconsistency.