chromium/tools/perf/contrib/vr_benchmarks/data/key_mobile_sites/README

This is a copy of the key_mobile_sites WPR archives from
//tools/perf/page_sets/data. We want to re-use the same archives for our
smoothness benchmark as the regular smoothness benchmark, but we also need to
add some new archives that are VR-specific/not useful for the non-VR benchmark.
So, copy the .sha1s and JSON file so we can download the pre-existing data while
being free to add new archives as we need.