"Allow aliases in enums" shows up in first enum description

[thomassedlmayer]

For every enum where allow_alias is set to true, the comment above this line gets added to the first enum description in the class reference docs.

https://github.com/OpenSimulationInterface/open-simulation-interface/blob/2c3953b377673e92ee2846a5471bf257d37e6154/osi_object.proto#L226C1-L228C39