Improve formulation in 'first_figure.py'

Author: yvonnefroehlich

examples/get-started/first_figure.py

@@ -37,8 +37,8 @@
 fig = pygmt.Figure()
 
 ###############################################################################
-# To add to a plot object (``fig`` in this example), the PyGMT module is used
-# as a method on the class. This example will use the
+# To add elements to the figure instance or object (``fig`` in this example)
+# different methods can be called on it. This example will use the
 # :meth:`pygmt.Figure.coast` method, which can be used to create a map without
 # any other methods or external data. The :meth:`pygmt.Figure.coast`
 # method plots the coastlines, borders, and bodies of water using a database