Document the Elixir override config source (#549)
Document the Elixir override config source (#549)

* Document the Elixir override config source

As discussed in https://github.com/appsignal/integration-guide/pull/128
we've added the "override" config source. Document this source in the
documentation load order page. This gets linked to from the diagnose
report viewer on AppSignal.com.

Part of https://github.com/appsignal/appsignal-elixir/issues/752

* Update source/elixir/configuration/load-order.html.md

Co-authored-by: Luismi Ramírez <7603dc0206be449a6e3cb127088e855d31f62d67@appsignal.com>
appsignal/appsignal-docs