Clarify ctrl-u.

Fixes #25.

README.md

@@ -65,7 +65,7 @@ Notes:
 
 - In Bash, use **Tab** to complete arguments and **ctrl-r** to search through command history.
 
-- In Bash, use **ctrl-w** to delete the last word, and **ctrl-u** to delete the whole line. Use **alt-b** and **alt-f** to move by word, **ctrl-k** to kill to the end of the line, **ctrl-l** to clear the screen. See `man readline` for all the default keybindings in Bash. There are a lot. For example **alt-.** cycles through previous arguments, and **alt-*** expands a glob.
+- In Bash, use **ctrl-w** to delete the last word, and **ctrl-u** to delete all the way back to the start of the line. Use **alt-b** and **alt-f** to move by word, **ctrl-k** to kill to the end of the line, **ctrl-l** to clear the screen. See `man readline` for all the default keybindings in Bash. There are a lot. For example **alt-.** cycles through previous arguments, and **alt-*** expands a glob.
 
 - Alternatively, if you love vi-style key-bindings, use `set -o vi`.