Several reviewers kindly provided feedback via IRC tonight, resulting in
the following changes:
* Mention that compressed keys are used in the offical secp256k1
documentation with the prefix bytes used by Bitcoin. I could not find
a publicly-available officialish document defining the prefix bytes,
but they're used repeatedly in the offical SECG documentation we
autoxref "secp256k1" to, so I went with that.
* Remove the mention that Bitcoin Core uses OpenSSL. While true, there
is an effort to slowly move away from using OpenSSL for EC in
Bitcoin Core.
* Change the phrasing of the relative curve location for 0x02 & 0x03 to
a form more correct for actuality instead of the illustrated
abstraction.
* Drop quotes around "uncompressed" since that's the term used in the
official secp256k1 docs, not something Bitcoin-specific.
8a9abffe6a