Update wrt parameter description to specify str type

Author: A-CGray

pyoptsparse/pyOpt_optimization.py

@@ -406,7 +406,7 @@ def addConGroup(
 
                 jac = {"dvName" : A, ...}, lower = gL - b, upper = gU - b
 
-        wrt : iterable (list, set, OrderedDict, array etc), optional
+        wrt : iterable of str, optional
             'wrt' stands for 'With Respect To'. This specifies which dvs this constraint is assumed to depend on, and
             therefore which blocks of the Jacobian will have non-zero values. The order is not important. By default the
             constraint is assumed to depend on all design variables.