mono-docs: Allow property refs with keys

mono-docs: Allow property refs with keys

When an EO property had multiple values or keys the C# generator
didn't generate a wrapping C# property. Therefore property references
in the documentation were changed to references to the getter.
Now multiple values are handled through tuples so the wrapping properties
ARE generated.
This patch removes the restriction for multiple values to doc refs
can more naturally reference the property instead of the getter method.
Properties with keys still reference the getter, since these are not wrapped.