clarifications in structured concurrency overview

[John Belmonte]

https://wiki.openjdk.java.net/display/loom/Structured+Concurrency

The Cancellation section doesn't mention what the default option is-- would
someone add a clarification?

Also, there is a typo in one of the code samples:  PROPAGTE_CANCEL
--> PROPAGATE_CANCEL

Thank you

(Not being able to edit, comment, or file a bug against documentation
without an OpenJDK account seems prohibitive-- it took me a while to track
down this list.)