openssl.pod: Add documentation for using the loader_attic engine

Reviewed-by: Tomas Mraz <tomas@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/13551)

diff --git a/doc/man1/openssl.pod b/doc/man1/openssl.pod
index 16b7769ae33e636d34444a7fbeb5eaf82a5e99dd..3176c19eee92528a7caa593636f50bdf67a3cbf7 100644 (file)
--- a/doc/man1/openssl.pod
+++ b/doc/man1/openssl.pod
@@ -615,6 +615,12 @@ L<config(5)/Engine Configuration>.
 The engine will be used for key ids specified with B<-key> and similar
 options when an option like B<-keyform engine> is given.
 
+A special case is the C<loader_attic> engine, which
+is meant just for internal OpenSSL testing purposes and
+supports loading keys, parameters, certificates, and CRLs from files.
+When this engine is used, files with such credentials are read via this engine.
+Using the C<file:> schema is optional; a plain file (path) name will do.
+
 =back
 
 Options specifying keys, like B<-key> and similar, can use the generic