Update docs on lava-wait-all with a role
Update docs on lava-wait-all with a role

Separate the sections and add an example flow table to illustrate
how to plan a multinode job.

Change-Id: I78b20d4958b3cd29f0f922981b8a67ee56142a29

Linaro/lava-server,Linaro/lava-server,Linaro/lava-server,Linaro/lava-server