[webauthn] new commits pushed by akshayku

The following commits were just pushed by akshayku to https://github.com/w3c/webauthn:

* Add to sec cons a brief discussion of the sec properties accrued by authnr & client platform proximity (#1333)

* Add security consideration on client-authnr direct communication

See issue #1257
https://github.com/w3c/webauthn/issues/1257

* Address @equalsJeffH's review comments

* Add missing CSS class .figure-num-previous

* Rewrite proximity section shorter and discuss benefits of physical proximity

* Add commas suggested by @agl

Co-Authored-By: Adam Langley <agl@google.com>

Co-authored-by: Adam Langley <agl@imperialviolet.org>
  by Emil Lundberg
https://github.com/w3c/webauthn/commit/d54a92aacc2fd8767f5188e3543f5bad62a29aa7