Feature: Add append to array

[kenjones-cisco]

Adds the ability to append a value to an array instead of having to
know the index of the values within the array.

Resolves: #17

[Rambatino]

Is this in the docs? I no can find.

[mikefarah]

http://mikefarah.github.io/yq/write/#appending-value-to-an-array-field

[Rambatino]

Thanks!

[Rambatino]

Can it support like passing a json object? The example is only one element, but I'd like to pass a nested structure to it.

[mikefarah]

Only one fields at a time:

yq n 'an.array[+].field.list[+].thing' apples

an:
  array:
  - field:
      list:
      - thing: apples

but you could use
http://mikefarah.github.io/yq/write/#updating-multiple-values-with-a-script
to add multiples

[Rambatino]

Thanks @mikefarah!