Incorrect documentation for toolbar-add-item

[smitchel]

The documentation for toolbar-add-item stated that it took a 
toolbar-spec for its first argument, and returned a (modified) 
toolbar-spec. However, it seems that what the function actually does is 
take a toolbar instance, and return a modified toolbar instance. I 
modified the name of the input variable, and changed the documentation 
string. The function should (and seems to) operate the same as before.

This was tested on:
XEmacs 21.4.21 for Windows x86
XEmacs 21.4.22 for Linux amd64

Sincerely,
Byrel Mitchell