Constraints doc edits (#5504)
Constraints doc edits (#5504)

* Constraints doc edits

* jdef's edits

* clarify field _name_ versus field _value_

* Jdef and Ivan's edits

meln1k/marathon,meln1k/marathon,mesosphere/marathon,gsantovena/marathon,meln1k/marathon,mesosphere/marathon,guenter/marathon,janisz/marathon,guenter/marathon,gsantovena/marathon,gsantovena/marathon,mesosphere/marathon,janisz/marathon,mesosphere/marathon,janisz/marathon,guenter/marathon,meln1k/marathon,guenter/marathon,meln1k/marathon,janisz/marathon,guenter/marathon,mesosphere/marathon,gsantovena/marathon,gsantovena/marathon,janisz/marathon