[openssl/openssl] 17345c: doc: fix EVP_SignInit.pod

[openssl-machine]

  Branch: refs/heads/openssl-3.0
  Home:   https://github.com/openssl/openssl
  Commit: 17345cf10f974d77bbb62015c8ab5f8962fc33f4
      https://github.com/openssl/openssl/commit/17345cf10f974d77bbb62015c8ab5f8962fc33f4
  Author: Reinhard Urban <reinhard.urban at nubix.de>
  Date:   2022-12-02 (Fri, 02 Dec 2022)

  Changed paths:
    M doc/man3/EVP_SignInit.pod

  Log Message:
  -----------
  doc: fix EVP_SignInit.pod

Fixes GH #19786

Also simplify the CSPRNG must be seeded argument.

Since version 1.1.1, the CSPRNG is seeded automatically on first use,
so it's not the responsibility of the programmer anymore.  Still, he
needs to be aware that the seeding might fail.

Reviewed-by: Matt Caswell <matt at openssl.org>
Reviewed-by: Tomas Mraz <tomas at openssl.org>
(Merged from https://github.com/openssl/openssl/pull/19789)

(cherry picked from commit 328dc33365f8bd9c097bc95c3632467f690502a4)