~/.xmonad: Support restarting.

I thought there was a default binding?

.xmonad/xmonad.hs

     } `additionalKeys` [
        ((mod4Mask, xK_b), spawnHere "chromium --allow-file-access-from-files"),
        ((mod4Mask .|. shiftMask, xK_b), spawnHere "chromium --incognito --allow-file-access-from-files"),
        ((mod4Mask .|. shiftMask, xK_Tab), changeKbMap kbMap),
        ((mod4Mask .|. shiftMask, xK_l), spawn "slock")
        ((mod4Mask .|. shiftMask, xK_l), spawn "slock"),
        ((mod4Mask, xK_q), restart "xmonad" True)
     ]
  where changeKbMap kbMap = do
          kb <- readIORef kbMap