Documentation: if-else semantics

[salotz]

The description here is really incomplete in using the if/else templating.

For instance its not clear about how this actually gets expanded and the example only covers lists.

For instance it is really confusing that this doesn't work:

group:
  normal_key: 1
  $if: true
  $then:
    some_other_key: 0

or

group:
  - item1
  $if: true
  $then:
    - item2

When you actually must put in the map/list in all or nothing like:

group:
  $if: true
  $then:
    normal_key: 1
    some_other_key: 0
  $else:
    normal_key: 1

I don't like the duplication that occurs because of this (another issue perhaps) but would be good to at least have the current behavior documented and show some useful examples of the most common gotcha. Feel free to use these examples!

[twelvemo]

Thanks for filing this issue, we really care about documentation and are super happy about feedback there.

[stefreak]

@salotz you can use the $merge and $concat operators to prevent duplication:

group:
  normal_key: 1
  $merge:
    $if: true
    $then:
      some_other_key: 0

and

group:
  - item1
  - $concat:
      $if: true
      $then:
        - item2

[salotz]

@stefreak I will look into those. I did discover them after the fact of writing this issue.