ssl_cache: Improve some comments

Signed-off-by: Pengyu Lv <pengyu.lv@arm.com>
diff --git a/programs/ssl/ssl_server2.c b/programs/ssl/ssl_server2.c
index 8277dde..d68f002 100644
--- a/programs/ssl/ssl_server2.c
+++ b/programs/ssl/ssl_server2.c
@@ -669,7 +669,7 @@
 #if defined(MBEDTLS_HAVE_TIME)
     int cache_timeout;          /* expiration delay of session cache entries*/
 #endif
-    int cache_remove;           /* enable / disable cache removement        */
+    int cache_remove;           /* enable / disable cache entry removal     */
     char *sni;                  /* string describing sni information        */
     const char *curves;         /* list of supported elliptic curves        */
     const char *sig_algs;       /* supported TLS 1.3 signature algorithms   */