Clarify that the "color" parameter in plot/plot3d can be 1d array (#1260)

Author: core-man

pygmt/helpers/decorators.py

@@ -37,7 +37,7 @@
            (e.g., *color1*,\ *color2*,\ *color3*) to build a linear continuous
            CPT from those colors automatically.""",
     "G": """\
-        color : str
+        color : str or 1d array
             Select color or pattern for filling of symbols or polygons. Default
             is no fill.""",
     "V": """\

pygmt/src/plot.py

@@ -146,6 +146,8 @@ def plot(self, x=None, y=None, data=None, size=None, direction=None, **kwargs):
         the coordinates of a *refpoint* which will serve as a fixed external
         reference point for all groups.
     {G}
+        *color* can be a 1d array, but it is only valid if using ``x``/``y``
+        and ``cmap=True`` is also required.
     intensity : float or bool or 1d array
         Provide an *intensity* value (nominally in the -1 to +1 range) to
         modulate the fill color by simulating illumination. If using

pygmt/src/plot3d.py

@@ -113,6 +113,8 @@ def plot3d(
         Offset the plot symbol or line locations by the given amounts
         *dx*/*dy*\ [/*dz*] [Default is no offset].
     {G}
+        *color* can be a 1d array, but it is only valid if using ``x``/``y``
+        and ``cmap=True`` is also required.
     intensity : float or bool or 1d array
         Provide an *intensity* value (nominally in the -1 to +1 range) to
         modulate the fill color by simulating illumination. If using