Verification Strategy update

[MikeOpenHWGroup]

Phase 1 of a big re-org before moving this out of core-v-docs into core-v-verif.

[DBees]

"It is also informative to consider the on-going Ibex project, another open-source RISC-V project derived from the ‘zero-riscy’ PULP-Platform core."

Does the write up reflect the Ibex project as of early 2020? To avoid potential confusion to the reader who would be reading this at some future point, maybe say "as of xyz date" rather than on-going.

Also, if you are adding new content, should put @copyright 2021 where appropriate

[MikeOpenHWGroup]

Good feedback @DBees, thanks. I've pushed in a couple of updates to respond to your comments.