doc: Add a note explaining a potential Dein version mismatch issue
doc: Add a note explaining a potential Dein version mismatch issue

Signed-off-by: Greg Hurrell <79e2475f81a6317276bf7cbb3958b20d289b78df@hurrell.net>

yrro/command-t,wincent/command-t,wincent/command-t,wincent/command-t,yrro/command-t