[openssl/openssl] 8a315d: Document SSL_R_UNEXPECTED_EOF_WHILE_READING

[Matt Caswell]

  Branch: refs/heads/openssl-3.0
  Home:   https://github.com/openssl/openssl
  Commit: 8a315d644107dce90e19b51edd799a2796fd2239
      https://github.com/openssl/openssl/commit/8a315d644107dce90e19b51edd799a2796fd2239
  Author: Matt Caswell <matt at openssl.org>
  Date:   2024-01-19 (Fri, 19 Jan 2024)

  Changed paths:
    M doc/man3/SSL_get_error.pod
    M ssl/record/rec_layer_s3.c

  Log Message:
  -----------
  Document SSL_R_UNEXPECTED_EOF_WHILE_READING

Also document that it is ok to use this for control flow decisions.

Reviewed-by: Tom Cosgrove <tom.cosgrove at arm.com>
Reviewed-by: Tomas Mraz <tomas at openssl.org>
(Merged from https://github.com/openssl/openssl/pull/23327)

(cherry picked from commit b7275c5e5c1c7b025bf2eb74fd1344b6abe48c06)