Update README.md

[druud]

1000 = k, not K.

[evanmiller]

Depends on the locale :-)

[druud]

I would just follow
https://en.wikipedia.org/wiki/International_System_of_Units
(in which K means Kelvin)

To me, "mb" reads as millibits.
Network speeds are generally either in kb/s (kilobits per second) or in Mb/s (megabits per second),
with alternative spellings: kbps, Mbps. When spelled as mbps, it must be very slow.