Make information about timeoutlen more explicit

[fuine]

I'm trying to set up this plugin and I just spent a hefty amount of time debugging a ghost popup (vim would wait indefinitely until I pressed <ESC> and then flash the guide, closing it instantly). I got it resolved by removing set notimeout from my .vimrc. After I got it to work I found this line in the README:

After pressing leader the guide buffer will pop up when there are no further keystrokes within timeoutlen.

I think that if you made this line more explicit (e.g. bold and/or bigger) it would potentially save some time and nerves clumsy people like me :)

Thanks for the great plugin!

[Tehnix]

Yeah, it can catch you if you miss it.

I'm personally running with

set timeoutlen=300
set ttimeoutlen=0

in my project for it :)