i2d_PublicKey was listed in 2 different man pages

find-doc-nits complains if a symbol is documented in more than one
location.
Reviewed-by: NRichard Levitte <levitte@openssl.org>

(cherry picked from commit 4ff4e53f816855b07fc02dc931dd57b2ae324aa1)
Reviewed-by: NTomas Mraz <tmraz@fedoraproject.org>
Reviewed-by: NMatthias St. Pierre <Matthias.St.Pierre@ncp-e.com>
(Merged from https://github.com/openssl/openssl/pull/10094)

doc/man3/d2i_X509.pod

@@ -307,7 +307,6 @@ i2d_POLICYQUALINFO,
 i2d_PROFESSION_INFO,
 i2d_PROXY_CERT_INFO_EXTENSION,
 i2d_PROXY_POLICY,
-i2d_PublicKey,
 i2d_RSAPrivateKey,
 i2d_RSAPrivateKey_bio,
 i2d_RSAPrivateKey_fp,