Document |SSL_set1_host| return values.

Change-Id: I9ba12ad7b3cfc9a6d1015da728cec45e4b71dcc9
Reviewed-on: https://boringssl-review.googlesource.com/c/boringssl/+/50665
Commit-Queue: Adam Langley <agl@google.com>
Reviewed-by: David Benjamin <davidben@google.com>
Commit-Queue: David Benjamin <davidben@google.com>
diff --git a/include/openssl/ssl.h b/include/openssl/ssl.h
index 29d825b..232c627 100644
--- a/include/openssl/ssl.h
+++ b/include/openssl/ssl.h
@@ -2460,7 +2460,7 @@
     int ok, X509_STORE_CTX *store_ctx);
 
 // SSL_set1_host sets a DNS name that will be required to be present in the
-// verified leaf certificate.
+// verified leaf certificate. It returns one on success and zero on error.
 //
 // Note: unless _some_ name checking is performed, certificate validation is
 // ineffective. Simply checking that a host has some certificate from a CA is