Docs: OCI Support design docs (#2589)

* Starting to fill in oci design doc

* Updates to design doc

* Formatting updates

* Updating title

* Adding why

* Update 01-oci-support.md

* Update 01-oci-support.md

* Docs: Adding yaml examples to kpt pkg update

* Docs: add descriptions of pkg pull/push

Also adds kpt pkg copy as an alternative

* Update 01-oci-support.md

Adding comparison of get vs pull

* Update 01-oci-support.md

Updating the descriptions of `kpt pkg pull` and `kpt pkg push`

Co-authored-by: Louis DeJardin <[email protected]>

Author: loudej