Update Session.hx (#5116)

Nobody seemed to have issues with this (since 2010), todo can be removed... Let's use the description of php manual..

std/php/Session.hx

@@ -20,8 +20,10 @@
  * DEALINGS IN THE SOFTWARE.
  */
 package php;
+
 /**
-* TODO: TEST IT!
+	Session consists of a way to preserve certain data across 
+	subsequent accesses.
 */
 class Session {
 	public static function getCacheLimiter() {
@@ -163,4 +165,4 @@ enum CacheLimiter {
 	Private;
 	NoCache;
 	PrivateNoExpire;
-}
+}