Readme.md: Add CI build status badges

Readme.md: Add CI build status badges

https://bugzilla.tianocore.org/show_bug.cgi?id=2315

Update Readme.md with status badges from the most recent
EDK II Continuous Integration(CI) build.

Cc: Andrew Fish <afish@apple.com>
Cc: Laszlo Ersek <lersek@redhat.com>
Cc: Leif Lindholm <leif.lindholm@linaro.org>
Signed-off-by: Michael D Kinney <michael.d.kinney@intel.com>
Acked-by: Laszlo Ersek <lersek@redhat.com>
Reviewed-by: Liming Gao <liming.gao@intel.com>
Reviewed-by: Leif Lindholm <leif.lindholm@linaro.org>