Update copyright year

Reviewed-by: Tomas Mraz <tomas@openssl.org>
Release: yes

Fix typos

Reviewed-by: Tim Hudson <tjh@openssl.org>
Reviewed-by: Tomas Mraz <tomas@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/17392)

Document the new core BIO public API support

Fixes #14409

Reviewed-by: Tomas Mraz <tomas@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/15072)