No `OnIdle` handler in the schema.

[jrbeaumont]

virtual-graph-schema-v2.rnc does not contain an OnIdle handler. No other schemas in the master directory contain an OnIdle handler either.

[m8pple]

What about OnCompute? It may just be that I'm being lazy talking about OnIdle, and if
it is mentioned anywhere it should be changed.

[jrbeaumont]

This line is the beginning of the OnCompute in v2.

[jrbeaumont]

From what I can find, the OnIdle handler is discussed in the orchestrator document, and OnCompute is not. I cannot find much else, at least with my searching, about OnIdle.