More complete instructions for building hail on spark clusters (#10756)
More complete instructions for building hail on spark clusters (#10756)

* More complete instructions for building hail on nonstandard clusters

* Suggestion for a common problem

* Don't want make to say it failed if hail wasn't initially installed

* Update docs to suggest building with Spark 3 instead

* Or true was unnecessary
hail-is/hail,hail-is/hail,hail-is/hail,hail-is/hail,hail-is/hail,hail-is/hail,hail-is/hail,hail-is/hail