DOC: Fix type annotation for order parameter in Epochs.plot() (#13639)

Co-authored-by: Daniel McCloy <dan@mccloy.info>
Co-authored-by: Scott Huberty <52462026+scott-huberty@users.noreply.github.com>

Author: 3 people

mne/viz/epochs.py

@@ -800,8 +800,12 @@ def plot_epochs(
             The new equivalent is ``events=False``.
     %(event_color)s
         Defaults to ``None``.
-    order : array of str | None
-        Order in which to plot channel types.
+    order : array-like of int | None
+        Order in which to plot data. If the array is shorter than the number of
+        channels, only the given channels are plotted. If ``None`` (default), all
+        channels are plotted. If ``group_by`` is ``'position'`` or
+        ``'selection'``, the ``order`` parameter is used only for selecting the
+        channels to be plotted.
 
         .. versionadded:: 0.18.0
     show : bool