doc: fix NAME section formatting in EVP_SIGNATURE documentation

doc: fix NAME section formatting in EVP_SIGNATURE documentation

Ensure consistent formatting in NAME sections across all EVP_SIGNATURE
documentation pages. The algorithm name should be bold (B<ALG>) rather
than EVP_PKEY, following the pattern:
"- The EVP_PKEY B<ALG> signature implementation"

Fixes #29328

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>
Reviewed-by: Paul Dale <paul.dale@oracle.com>
Reviewed-by: Shane Lontis <shane.lontis@oracle.com>
Reviewed-by: Tomas Mraz <tomas@openssl.org>
MergeDate: Fri Feb 13 15:09:54 2026
(Merged from https://github.com/openssl/openssl/pull/29789)