Fix example usage in method-proxy-js post

The `.push()` method does not expect the second element of its array
argument to be an object, rather it expects an array of arbitrary length
where each element beyond the first is an argument to be passed to the
method.

Change-Id: Icd9553bab1d4e85977bae9ee7e8e2a17723520bc
Reviewed-on: https://gerrit.causes.com/26322
Tested-by: jenkins <jenkins@causes.com>
Reviewed-by: Kim Douglas Clarence Mason <kim.mason@causes.com>