docs: workflow inputs #11

{"all":True, "name":"a", "value":11}
this gives a=11 to all tasks

{"all":False, "name":"a", "value":11}
this gives a=11 to all input tasks (i.e. nodes without a predecessor in the graph)

{"id":"task1", "name":"a", "value":11}
this gives a=11 to one specific task