README.md: updated
README.md: updated

The contents of the README.md are updated to reflect the current
project.

Change-Id: I8461f50c4468a0f2b206a93a36e88d09b5e5f871
Reviewed-on: https://go-review.googlesource.com/c/vuln/+/360440
Trust: Julie Qiu <8d32267b6b4884cf35adeaccde2b6857ae11aace@golang.org>
Reviewed-by: Jonathan Amsterdam <e3d3698b2ccd5955e4adf250d0785062d0f9018b@google.com>

golang/vuln,golang/vuln