Add includes in synopsis.
Submitted by: Mike Frysinger <vapier@gentoo.org>
diff --git a/doc/crypto/OBJ_nid2obj.pod b/doc/crypto/OBJ_nid2obj.pod
index 7dcc079..1e45dd4 100644
--- a/doc/crypto/OBJ_nid2obj.pod
+++ b/doc/crypto/OBJ_nid2obj.pod
@@ -8,6 +8,8 @@
 
 =head1 SYNOPSIS
 
+ #include <openssl/objects.h>
+
  ASN1_OBJECT * OBJ_nid2obj(int n);
  const char *  OBJ_nid2ln(int n);
  const char *  OBJ_nid2sn(int n);