remove removed functions from docs

Author: Christopher Rowley

docs/src/pythoncall-reference.md

@@ -250,12 +250,7 @@ The functions here are not exported. They are mostly unsafe in the sense that yo
 crash Julia by using them incorrectly.
 
 ```@docs
-PythonCall.pynew
-PythonCall.pyisnull
-PythonCall.pycopy!
-PythonCall.getptr
 PythonCall.pydel!
-PythonCall.unsafe_pynext
 ```
 
 ## NumpyDates