docs: charm constraints page refers to unsupported 'maas-name' constraint

[Dave Cheney]

https://juju.ubuntu.com/docs/charms-constraints.html

The currently available MAAS constraint is:

maas-name: The MAAS name to which each unit must be deployed. This is philosophically problematic, on the basis that teaching users that it's OK to specify single machines will lead them to pain when they attempt to scale out large deployments; but it's justified on the basis that MAAS itself needs to act as a stepping stone between the "metal" and "cloud" mindsets. maas-name is unset by default, and should correspond to a name known by the MAAS provider.

^ this is not true, juju 1.12/1.13 does not support any form of provider specific constraints, only the generic cpu-cores, memory, and arch constraints

[Nick Veitch (evilnick)]

sorry, this was actually fixed a while back, but slipped through my radar because it wasn't targetted to Docs.