feat: add word and WORD motions

src/main.rs

@@ -9,6 +9,7 @@ Usage: vamp [--config PATH | --no-config] [FILE]
 Default keys (configurable with config.bind):
 Normal: i/a insert, I/A insert at first nonblank/end, o/O new line
         h/j/k/l move, 0/$ line ends, x delete, J join lines
+        w/b/e word next/previous/end, W/B/E whitespace-delimited WORDs
         u undo, U redo, : command, / search, n/N next/previous match
 Insert: Esc returns to normal
 Search: Enter finds next literal match, Esc cancels (case-sensitive, wraps)