readme: |

  =====================
  Appending Array Items
  =====================

  In ytt v0.32.0+, array items without a matching annotation
  are appended to the end of the list. This operation ignores
  other overlay annotations and always inserts after the last
  item.

  All other array item operations must specify how to match
  as they are not indexed by keys. Do so using the same
  `#@overlay/match by=...` annotation used on documents.

  So, all of the following action annotations must be
  paired with a matching annotation (`@overlay/match`)

  - `@overlay/merge`
  - `@overlay/replace`
  - `@overlay/remove`
  - `@overlay/insert`


  ------------------------
  Append vs. Ensure Exists
  ------------------------

  `append-https-port.yml` showcases how to add new array
  items.

  Explore:
  1. Summarize what this overlay does in a sentence.

  2. Examine the output of `config/service.yml`; what's
     wrong there? (hint: ports must be unique)

  3. Just above line 8 in `append-https-port.yml` _add_ the following:
     ```
     #@overlay/remove
     #@overlay/match by="name", missing_ok=True
     - name: https
     ```

     How does `config/service.yml` look?

  4. Does the same possibility exist for the `Deployment`?


  ................
  Thinking in ytt:

  "Overlays apply not to collections, but items:

             not docsets, documents;
                          not maps, map items;
                                    not arrays, array items."
