implement keyboard initiated movement of windows

enhanced version of diff originally from niallo@
man bits from niallo@
ok niallo@ japser@

cwm.1

@@ -126,6 +126,13 @@ font string
 .Ar fontname
 the default font.
 .El
+.Sh WINDOW MOVEMENT
+.Nm
+windows can be moved with the use of the keyboard through Vi-like bindings.
+M-[hjkl] moves the current window a small amount, while M-shift-[hjkl] moves
+the current window a larger amount.
+For example, to move the current window to the left a small amount, press M-h.
+To move the current window down by a larger amount, press M-shift-j.
 .Sh SEARCH
 .Nm 
 features the ability to search for windows by their current title, old