Generate "generated by" doc-comments

[bernardnormier]

We currently "generated by" doc-comments in C# but not other languages. See for example:

https://code.zeroc.com/ice/main/api/cpp/classIce_1_1LocatorPrx.html#details
https://code.zeroc.com/ice/main/api/csharp/api/Ice.LocatorPrx.html#Ice_LocatorPrx_remarks
https://code.zeroc.com/ice/main/api/java/com.zeroc.ice/com/zeroc/Ice/LocatorPrx.html
https://code.zeroc.com/ice/main/api/javascript/Ice/LocatorPrx.html
https://code.zeroc.com/ice/main/api/php/classes/Ice-LocatorPrxHelper.html
https://code.zeroc.com/ice/main/api/python/Ice.html#Ice.LocatorPrx
https://code.zeroc.com/ice/main/api/ruby/Ice/LocatorPrx.html
https://code.zeroc.com/ice/main/api/swift/documentation/ice/locatorprx