#325 rexxref 2.3 CALL and chapter 11 should document namespaces

[Josep Maria Blasco]

In 2.3, "Call name" should be expanded to "( call [namespace:]symbol" | call string)".

Additionally, in chapter 11, the trapname of CALL ON currently does not support namespaces. My impression is that it should. Otherwise, the fact that they cannot be used should be documented.