This is merely a suggestion to also default the `ctrl-[` keymap to
close ex-mode. This behaviour is very similar to vim's default
behaviour:
```
CTRL-[ *c_CTRL-[* *c_<Esc>* *c_Esc*
<Esc> When typed and 'x' not present in 'cpoptions', quit
Command-line mode without executing. In macros or when 'x'
present in 'cpoptions', start entered command.
Note: If your <Esc> key is hard to hit on your keyboard, train
yourself to use CTRL-[.
```
Is very similar to the currently supported `ctrl-c`
```
CTRL-C *c_CTRL-C*
quit command-line without executing
```
