Add Python API docs for RebinParamsValidator

Framework/PythonInterface/mantid/kernel/src/Exports/RebinParamsValidator.cpp

@@ -26,5 +26,7 @@ void export_RebinParamsValidator() {
       .def("__init__",
            make_constructor(
                &createRebinParamsValidator, default_call_policies(),
-               (arg("AllowEmpty") = false, arg("AllowRange") = false)));
+               (arg("AllowEmpty") = false, arg("AllowRange") = false)),
+           "Constructs a validator verifying that the given float array is "
+           "valid sequence of rebinning parameters.");
 }

docs/source/api/python/mantid/kernel/RebinParamsValidator.rst

+======================
+ RebinParamsValidator
+======================
+
+This is a Python binding to the C++ class Mantid::Kernel::RebinParamsValidator.
+
+*bases:* :py:obj:`mantid.kernel.IValidator`
+
+.. module:`mantid.kernel`
+
+.. autoclass:: mantid.kernel.RebinParamsValidator 
+    :members:
+    :undoc-members:
+    :inherited-members:
+