Point the manual's white balance scene at "pick", and record it again

The scene clicked 40px to the right of "pick", on "reset", so the
recording showed a neutral group being reset and a click on the wall
that panned. Re-recorded with the picker fixed: the word lights, the
sample moves temperature and tint, and Before shows what it corrected.

tools/manual/scenes.py

@@ -207,7 +207,7 @@ def develop_wb():
     group('colour')
     rec('develop-wb')
     pause(0.4)
-    dr.click(1542, 767); pause(0.8)                    # pick
+    dr.click(1487, 776); pause(0.8)                    # pick
     dr.click(1000, 300); pause(1.5)                    # a neutral wall
     hold(*BEFORE, 1.4); pause(0.8)
     cut()