Updated docs for play/edit controls.

doc/2-interface/play-edit-controls.md

@@ -8,11 +8,12 @@ the "Play/Edit Controls" are used to control playback and change parameters of t
 - ![play repeat](control-play-repeat.png) **Repeat from the beginning of this pattern**: repeats current pattern from its start.
 - ![step](control-step.png) **Step one row**: plays only the row at cursor position and moves down one.
 - ![edit](control-edit.png) **Edit**: toggles edit mode. when turned off, you won't be able to enter notes.
+- ![lock](control-lock.png) **Lock**: toggles the cursor lock, which keeps the cursor in the currently selected order.
 - ![metronome](control-metronome.png) **Metronome**: toggles the metronome, which only works during playback.
 - ![repeat](control-repeat.png) **Repeat pattern**: toggles pattern repeat. during playback while this is on, the current pattern will play over and over instead of following the order list.
 - **Poly**: turns on polyphony for previewing notes. toggles to **Mono** for monophony (one note at a time only).
 - **Octave**: sets current input octave.
-- **Step**: sets edit step. if this is 1, entering a note or effect will move to the next row. if this is a larger number, rows will be skipped. if this is 0, the cursor will stay in place.
+- **Edit Step**: sets edit step. if this is 1, entering a note or effect will move to the next row. if this is a larger number, rows will be skipped. if this is 0, the cursor will stay in place.
   - if clicked, Step becomes **Coarse**, which sets the number of rows moved with `PgUp`, `PgDn`, and related movement shortcuts. clicking again will revert it to Step.
 - **Follow orders**: if on, the selected order in the orders window will follow the song during playback.
 - **Follow pattern**: if on, the cursor will follow playback and the song will scroll by as it plays.