[doc] remove some warning during doc generation

scheme/scheme.py

@@ -154,7 +154,7 @@ class Scheme(object):
         """
 
         :return: list of nodes starting the workflow. Those does not require
-        any input_data
+                 any input_data.
         :rtype: list
         """
         res = []
@@ -302,9 +302,10 @@ class Scheme(object):
 
         :param str json_file_path: path to the json file containing the scheme
                                    description
+
         :return: Scheme fitting the json description contains if the file.
                  If description is incomplete, return None
-        :rtype:Union[Scheme,None]
+        :rtype: Union[Scheme, None]
         """
         try:
             with open(json_file_path, 'r') as json_file:
@@ -378,7 +379,7 @@ class Scheme(object):
     def scheme_to_etree(self, data_format:str = "literal",
                         pickle_fallback: bool = False):
         """
-        Return an `xml.etree.ElementTree` representation of the `scheme.
+        Return an 'xml.etree.ElementTree' representation of the scheme.
         """
         builder = TreeBuilder(element_factory=Element)
         builder.start("scheme", {"version": "2.0",
@@ -562,9 +563,10 @@ class SubScheme(Scheme, Node):
     def load_from_json(json_data: dict):
         """
 
-        :param json_data: scheme description
+        :param json_data: scheme description.
+
         :raise ValueError: if sink or source channel missing or if link id
-                           missing or if sink or source node missing
+                           missing or if sink or source node missing.
         """
         nodes, links, sub_schemes, title, description = Scheme.load_scheme_info_from_json(json_data)
         _id, _properties, _process_pt = Node.load_node_info_from_json(json_data)