Documentation for ECProperty attributes lack examples

[ColinKerr]

https://www.itwinjs.org/bis/ec/ec-property/#additional-optional-attributes

There are no actual examples on this page. There should be at least one example for each property type in xml and in json. Every attribute should be included in at least one example in xml and json.

For properties like typeName that have a fixed set of allowable values those should be documented