WIP: DOC: Add gallery example for magnetic rose

examples/gallery/embellishments/magnetic_rose.py

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+"""
+Magnetic rose
+=============
+
+The method :meth:`pygmt.Figure.magnetic_rose` can be used to add a magnetic rose to a
+map. This example shows how such a magnetic rose can be customized.
+"""
+
+# %%
+import pygmt
+
+fig = pygmt.Figure()
+fig.basemap(region=[-8, 8, -7, 7], projection="M10c", frame=True)
+
+# Add a magnetic rose.
+# By default, it's placed in the lower left corner.
+fig.magnetic_rose()
+
+# Add a magnetic rose with several adjustments
+with pygmt.config(
+    # Pen used for the ticks related the outer circle and the outline of the North star
+    MAP_TICK_PEN_SECONDARY="orange",
+    # Pen used for the ticks related to the inner circle
+    MAP_TICK_PEN_PRIMARY="cyan",
+    # Pen used for the stem of the declination arrow and the fill of the North star
+    MAP_DEFAULT_PEN="brown",
+    # Font used for the labels for the geographic directions
+    FONT_TITLE="purple",
+):
+    fig.magnetic_rose(
+        position="MC",  # placed at MiddleCenter
+        width=4.5,  # width of the rose
+        # If a declination value is given, a arrow showing the declination is plotted
+        # instead of the simple North arrow
+        declination=14.3,
+        # Adjust the label added to the declination arrow
+        declination_label="14.3 N°E",
+        # Add labels for the geographic directions. Use a * to get a North star and
+        # "" to skip a label
+        labels=["W", "E", "South", "*"],
+        # Draw an outer circle with the provided pen
+        outer_pen="1p,red",
+        # Draw an inner circle with the provided pen
+        inner_pen="1p,blue",
+    )
+
+fig.show()