Fix a tiny typo in multi-parameter-symbols.py

Replaced "option" by "argument"

Author: michaelgrund

examples/gallery/plot/multi-parameter-symbols.py

@@ -3,7 +3,7 @@
 -------------------------
 
 The :meth:`pygmt.Figure.plot` method can plot individual multi-parameter symbols by passing 
-the corresponding shortcuts listed below to the ``style`` option. Additionally, we must define 
+the corresponding shortcuts listed below to the ``style`` argument. Additionally, we must define 
 the required parameters in a 2d list or numpy array (``[[parameters]]`` for a single symbol 
 or ``[[parameters_1],[parameters_2],[parameters_i]]`` for several ones) or use an 
 appropriately formatted input file and pass it to ``data``.