docs: Changing units to SI units in projections (#719)

examples/tutorials/contour-map.py

@@ -72,7 +72,7 @@
  interval=250,
  grid=grid,
  limit=[-4000, -2000],
- projection="M4i",
+ projection="M10c",
  frame=True,
 )
 fig.show()
@@ -85,14 +85,13 @@
 # colormap to the contour map. It must be called prior to
 # :meth:`pygmt.Figure.grdcontour` to keep the contour lines visible on the final map.
 # If the ``projection`` argument is specified in the :meth:`pygmt.Figure.grdimage`
-# method, it does not need to be repeated in
-# the :meth:`pygmt.Figure.grdcontour` method.
+# method, it does not need to be repeated in the :meth:`pygmt.Figure.grdcontour` method.
 
 fig = pygmt.Figure()
 fig.grdimage(
  grid=grid,
  cmap="haxby",
- projection="M4i",
+ projection="M10c",
  frame=True,
 )
 fig.grdcontour(