Adding range selection (i.e. SHIFT+Click) to documentation

Author: jonoomph

doc/clips.rst

@@ -109,6 +109,7 @@ Here is a list of all methods for selecting clips in OpenShot:
    **Box Selection**                         Click and drag a selection box around clips or transitions to select multiple items at once. Hold down :kbd:`Ctrl` to add to your current selection.
    **Click Selection**                       Click on a clip or transition to select it. This will deselect all other items unless you hold down :kbd:`Ctrl`.
    **Add to Selection**                      Hold down :kbd:`Ctrl` while clicking to add or remove clips from the current selection, allowing you to select non-adjacent clips.
+   **Range Selection**                       Hold down :kbd:`Shift` while clicking to select a range of clips/transitions from the previous selection to the new selection. This supports ranges that span multiple tracks as well.
    **Ripple Selection**                      Hold down :kbd:`Alt` while clicking to ripple select all clips/transitions from your selection to the end of the track. This always adds to your current selection, even if :kbd:`Ctrl` is not pressed.
    **Clear Selection**                       Click anywhere on the timeline or on a new clip/transition to reset the current selection, unless :kbd:`Ctrl` is pressed.
    **Select All**                            Press :kbd:`Ctrl+A` to select all clips and transitions on the timeline.