Readme.md: Change line endings from LF to CLRF

Fix for issue found when running patch check script

Contributed-under: TianoCore Contribution Agreement 1.1
Signed-off-by: Christopher Co <christopher.co@microsoft.com>
Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: Leif Lindholm <leif.lindholm@linaro.org>
Cc: Michael D Kinney <michael.d.kinney@intel.com>
Reviewed-by: Leif Lindholm <leif.lindholm@linaro.org>