Add multiple label support to plot() docstring

Author: yozhikoff

lib/matplotlib/axes/_axes.py

@@ -1499,6 +1499,8 @@ def plot(self, *args, scalex=True, scaley=True, data=None, **kwargs):
 
             If you make multiple lines with one plot call, the kwargs
             apply to all those lines.
+            In case if label object is iterable, each its element is
+            used as label for a separate line.
 
             Here is a list of available `.Line2D` properties: