g: add documentation pointing to p256 modular reduction verification in Coq
g: add documentation pointing to p256 modular reduction verification in Coq

Added a markdown file with some explanation and links to Coq code in a
public GitHub repository.

BUG=none
BRANCH=cr50
TEST=none

Change-Id: I4b40a94ce8686e5115b6b09825dfde0894d67a50
Signed-off-by: Jade Philipoom <23b156e860ef6ab36b055884a79031aa7723874a@google.com>
Reviewed-on: https://chromium-review.googlesource.com/1080795
Commit-Ready: Vincent Palatin <70a9964ec8fd10b0b08fcc8623c2add25ddf99ac@chromium.org>
Tested-by: Vincent Palatin <70a9964ec8fd10b0b08fcc8623c2add25ddf99ac@chromium.org>
Reviewed-by: Vincent Palatin <70a9964ec8fd10b0b08fcc8623c2add25ddf99ac@chromium.org>

coreboot/chrome-ec,coreboot/chrome-ec,coreboot/chrome-ec,coreboot/chrome-ec,coreboot/chrome-ec,coreboot/chrome-ec