Fix comment on session version field.

It is not ignored.

Change-Id: I2e607a6d6f7444838fc6fa65cd18e9aa142f139f
Reviewed-on: https://boringssl-review.googlesource.com/12023
Commit-Queue: David Benjamin <davidben@google.com>
Reviewed-by: Adam Langley <agl@google.com>

ssl/ssl_asn1.c

diff --git a/ssl/ssl_asn1.c b/ssl/ssl_asn1.c
index eeea826..f81450b 100644
--- a/ssl/ssl_asn1.c
+++ b/ssl/ssl_asn1.c
@@ -97,7 +97,7 @@
 /* An SSL_SESSION is serialized as the following ASN.1 structure:
  *
  * SSLSession ::= SEQUENCE {
- *     version                     INTEGER (1),  -- ignored
+ *     version                     INTEGER (1),  -- session structure version
  *     sslVersion                  INTEGER,      -- protocol version number
  *     cipher                      OCTET STRING, -- two bytes long
  *     sessionID                   OCTET STRING,