Include MIT license from known_chrome_flags.py and fix the typo in the
file name.

Change-Id: I3e2aaec244b058fca058382472c65d4c4f1aeb74
Reviewed-on: https://chromium-review.googlesource.com/c/crossbench/+/5782815


Reviewed-by: Patrick Thier <pthier@chromium.org>
Commit-Queue: Camillo Bruni <cbruni@chromium.org>