DOC: fix documentation of som EVP_MD_CTX functions

They were documented to take an EVP_MD pointer, when they really take
an EVP_MD_CTX pointer.

Fixes #9993

Reviewed-by: Matt Caswell <matt@openssl.org>
(Merged from #9996)

doc/man3/EVP_DigestInit.pod

@@ -68,9 +68,9 @@ EVP_MD_do_all_ex
 
  const EVP_MD *EVP_MD_CTX_md(const EVP_MD_CTX *ctx);
  const char *EVP_MD_CTX_name(const EVP_MD_CTX *ctx);
- int EVP_MD_CTX_size(const EVP_MD *ctx);
- int EVP_MD_CTX_block_size(const EVP_MD *ctx);
- int EVP_MD_CTX_type(const EVP_MD *ctx);
+ int EVP_MD_CTX_size(const EVP_MD_CTX *ctx);
+ int EVP_MD_CTX_block_size(const EVP_MD_CTX *ctx);
+ int EVP_MD_CTX_type(const EVP_MD_CTX *ctx);
  void *EVP_MD_CTX_md_data(const EVP_MD_CTX *ctx);
  int (*EVP_MD_CTX_update_fn(EVP_MD_CTX *ctx))(EVP_MD_CTX *ctx,
                                               const void *data, size_t count);