fix various issues

- fix CI failure due to wrong usage of ticket_lifetime
- Improve document and comments

Signed-off-by: Jerry Yu <jerry.h.yu@arm.com>
diff --git a/include/mbedtls/mbedtls_config.h b/include/mbedtls/mbedtls_config.h
index 4acac9c..407b31e 100644
--- a/include/mbedtls/mbedtls_config.h
+++ b/include/mbedtls/mbedtls_config.h
@@ -4099,7 +4099,7 @@
 /**
  * \def MBEDTLS_SSL_TLS1_3_TICKET_AGE_TOLERANCE
  *
- * Maximum allowd ticket age difference in milliseconds tolerated between
+ * Maximum allowed ticket age difference in milliseconds tolerated between
  * server and client. Default value is 6000. This is not used in TLS 1.2.
  *
  * - The client ticket age is the time difference between the time when the
@@ -4109,11 +4109,11 @@
  *   server receives a proposition from the client to use the ticket and the
  *   time when the ticket was created by the server.
  *
- * The ages might be different due to accuracy of RTC crypstal. The typical
- * accuracy of an RTC crystal is ±100 to ±20 parts per million (360 to 72
- * milliseconds per hour). Default tolerance windows is 6s, thus in the worst
- * case client and servers must sync up their system time every 6000/360/2~=8
- * hours.
+ * The ages might be different due to the client and server clocks not running
+ * at the same pace. The typical accuracy of an RTC crystal is ±100 to ±20 parts
+ * per million (360 to 72 milliseconds per hour). Default tolerance window is
+ * 6s, thus in the worst case clients and servers must sync up their system time
+ * every 6000/360/2~=8 hours.
  *
  */
 //#define MBEDTLS_SSL_TLS1_3_TICKET_AGE_TOLERANCE 6000
diff --git a/include/mbedtls/ssl.h b/include/mbedtls/ssl.h
index 3213a2b..07a9e88 100644
--- a/include/mbedtls/ssl.h
+++ b/include/mbedtls/ssl.h
@@ -1256,10 +1256,10 @@
 
 #if defined(MBEDTLS_HAVE_TIME)
 #if defined(MBEDTLS_SSL_CLI_C)
-    mbedtls_ms_time_t MBEDTLS_PRIVATE(ticket_reception_time);        /*!< time that ticket was received */
+    mbedtls_ms_time_t MBEDTLS_PRIVATE(ticket_reception_time);   /*!< time when ticket was received. */
 #endif
 #if defined(MBEDTLS_SSL_SRV_C)
-    mbedtls_ms_time_t MBEDTLS_PRIVATE(ticket_creation_time);     /*!< create time of ticket */
+    mbedtls_ms_time_t MBEDTLS_PRIVATE(ticket_creation_time);    /*!< time when ticket was created. */
 #endif
 #endif /* MBEDTLS_HAVE_TIME */