Adjust documentation of roads example (#2799)

Author: michaelgrund

examples/gallery/lines/roads.py

@@ -6,7 +6,7 @@
 as lines which are stored in a :class:`geopandas.GeoDataFrame` object. Use
 :func:`geopandas.read_file` to load data from any supported OGR format such as
 a shapefile (.shp), GeoJSON (.geojson), geopackage (.gpkg), etc. Then, pass the
-:class:`geopandas.GeoDataFrame` as an argument to the ``data`` parameter in
+:class:`geopandas.GeoDataFrame` as an argument to the ``data`` parameter of
 :meth:`pygmt.Figure.plot`, and style the geometry using the ``pen`` parameter.
 """