Document functions acting on an SSL_SESSION.

Change-Id: I0b4386d1972af0ac10db397716de8161810a87f4
Reviewed-on: https://boringssl-review.googlesource.com/5877
Reviewed-by: Adam Langley <agl@google.com>

ssl/ssl_lib.c

diff --git a/ssl/ssl_lib.c b/ssl/ssl_lib.c
index 9672e8c..a70d55a 100644
--- a/ssl/ssl_lib.c
+++ b/ssl/ssl_lib.c
@@ -2050,8 +2050,8 @@
   return ssl_get_version(s->version);
 }
 
-const char *SSL_SESSION_get_version(const SSL_SESSION *sess) {
-  return ssl_get_version(sess->ssl_version);
+const char *SSL_SESSION_get_version(const SSL_SESSION *session) {
+  return ssl_get_version(session->ssl_version);
 }
 
 const char* SSL_get_curve_name(uint16_t curve_id) {