doc: EVP_DigestInit clears all flags

Mention that EVP_DigestInit() also clears all flags.

Fixes: 10031
Signed-off-by: NChristian Heimes <christian@python.org>
Reviewed-by: NTomas Mraz <tmraz@fedoraproject.org>
Reviewed-by: NPaul Dale <paul.dale@oracle.com>
(Merged from https://github.com/openssl/openssl/pull/10032)

(cherry picked from commit 091aab66a6dbc3a3ecee7684aa30811b342f04e7)

doc/man3/EVP_DigestInit.pod

@@ -122,7 +122,7 @@ few bytes.
 =item EVP_DigestInit()
 
 Behaves in the same way as EVP_DigestInit_ex() except it always uses the
-default digest implementation.
+default digest implementation and calls EVP_MD_CTX_reset().
 
 =item EVP_DigestFinal()