Remove class title underline from operator template (#1985)

Following changes made to fix problems in the API documentation.

Author: PProfizi

src/ansys/dpf/core/operators/operator.mustache

@@ -1,6 +1,6 @@
 """
 {{class_name}}
-{{class_name_underlining}}
+
 Autogenerated DPF operator classes.
 """
 
@@ -259,4 +259,4 @@ class Outputs{{capital_class_name}}(_Outputs):
         >>> result_{{name}} = op.outputs.{{name}}()
         """ # noqa: E501
         return self._{{name}}
-    {{/multiple_types}}{{/output_pins}}
+    {{/multiple_types}}{{/output_pins}}