add docstrings for nodemarkers

_pytest/mark/structures.py

@@ -369,6 +369,14 @@ class NodeKeywords(MappingMixin):
 
 @attr.s(cmp=False, hash=False)
 class NodeMarkers(object):
+    """
+    internal strucutre for storing marks belongong to a node
+
+    ..warning::
+
+        unstable api
+
+    """
     own_markers = attr.ib(default=attr.Factory(list))
 
     def update(self, add_markers):

_pytest/nodes.py

@@ -183,7 +183,10 @@ class Node(object):
         self._markers.update([marker])
 
     def find_markers(self, name):
-        """find all marks with the given name on the node and its parents"""
+        """find all marks with the given name on the node and its parents
+
+        :param str name: name of the marker
+        """
         for node in reversed(self.listchain()):
             for mark in node._markers.find(name):
                 yield mark