Update gallery example

Author: yvonnefroehlich

examples/gallery/images/grdlandmask.py

@@ -3,7 +3,7 @@
 ==========================
 
 The :func:`pygmt.grdlandmask` function allows setting all nodes on land
-or water to a specified value using the ``maskvalues`` parameter.
+or water to a specified value using the ``mask_values`` parameter.
 """
 
 # %%
@@ -18,7 +18,9 @@
 # masses.
 # Use shoreline data with (l)ow resolution and set the grid spacing to
 # 5 arc-minutes in x- and y-directions.
-grid = pygmt.grdlandmask(region=region, spacing="5m", maskvalues=[0, 1], resolution="l")
+grid = pygmt.grdlandmask(
+    region=region, spacing="5m", mask_values=[0, 1], resolution="l"
+)
 
 # Plot clipped grid
 fig.basemap(region=region, projection="M12c", frame=True)