Fix typo symbol to style

Co-Authored-By: Dongdong Tian <seisman.info@gmail.com>

pygmt/base_plotting.py

@@ -646,13 +646,12 @@ def plot(self, x=None, y=None, data=None, sizes=None, direction=None, **kwargs):
         If a symbol is selected and no symbol size given, then plot will
         interpret the third column of the input data as symbol size. Symbols
         whose size is <= 0 are skipped. If no symbols are specified then the
-        symbol code (see **symbol** below) must be present as last column in
-        the input. If **symbol** is not used, a line connecting the data points
-        will be drawn instead. To explicitly close polygons, use **close**.
-        Select a fill with **color**. If **color** is set, **pen** will control
-        whether the polygon outline is drawn or not. If a symbol is selected,
-        **color** and **pen** determines the fill and outline/no outline,
-        respectively.
+        symbol code (see **style** below) must be present as last column in the
+        input. If **style** is not used, a line connecting the data points will
+        be drawn instead. To explicitly close polygons, use **close**. Select a
+        fill with **color**. If **color** is set, **pen** will control whether
+        the polygon outline is drawn or not. If a symbol is selected, **color**
+        and **pen** determines the fill and outline/no outline, respectively.
 
         Full option list at :gmt-docs:`plot.html`