Scaladocs about liburary-aux is broken

As it is, Seems like scaladoc could not got the parameter names when generating the document.

scala 2.13.0-M5> "hello".==(that = "world")
                                 ^
                 error: unknown parameter name: that

scala 2.13.0-M5> "hello".==(arg0 = "world")
                                 ^
                 error: unknown parameter name: arg0

scala 2.13.0-M5> "hello".==
   final def ==(x$1: Any): Boolean

scala 2.13.0-M5> "hello".==(x$1 = "world")
                                ^
                 error: unknown parameter name: x$1