Figure.histogram: Let parameter 'cumulative' support Pythonic arguments

pygmt/src/histogram.py

@@ -24,7 +24,6 @@
     F="center",
     L="extreme",
     N="distribution",
-    Q="cumulative",
     S="stairs",
     T="series",
     Z="histtype",
@@ -45,6 +44,7 @@ def histogram(
     pen: str | None = None,
     fill: str | None = None,
     horizontal: bool = False,
+    cumulative: bool | Literal["reverse"] = False,
     projection: str | None = None,
     region: Sequence[float | str] | str | None = None,
     frame: Frame | Axis | Literal["none"] | str | Sequence[str] | bool = False,
@@ -68,6 +68,7 @@ def histogram(
        - E = bar_width, **+o**: bar_offset
        - G = fill
        - J = projection
+       - Q = cumulative
        - R = region
        - V = verbose
        - W = pen
@@ -113,10 +114,9 @@ def histogram(
         * 0 = mean and standard deviation [Default];
         * 1 = median and L1 scale (1.4826 \* median absolute deviation; MAD);
         * 2 = LMS (least median of squares) mode and scale.
-    cumulative : bool or str
-        [**r**].
-        Draw a cumulative histogram by passing ``True``. Use **r** to display
-        a reverse cumulative histogram.
+    cumulative
+        Pass ``True`` to draw a cumulative histogram, or set it to ``"reverse"`` to draw
+        a reverse cumulative histogram instead.
     extreme : str
         **l**\|\ **h**\|\ **b**.
         The modifiers specify the handling of extreme values that fall outside
@@ -176,6 +176,7 @@ def histogram(
             Alias(bar_offset, name="bar_offset", prefix="+o"),
         ],
         G=Alias(fill, name="fill"),
+        Q=Alias(cumulative, name="cumulative", mapping={"reverse": "r"}),
         W=Alias(pen, name="pen"),
     ).add_common(
         B=frame,