add metadata

Author: alimanfoo

slides/v3-update-20190619.html

@@ -42,6 +42,12 @@
 			.reveal p, .reveal li {
 			        font-size: 0.9em;
 			}
+			.reveal pre {
+			font-size: 0.5em;
+			}
+			.reveal pre code {
+			max-height: 600px;
+			}
                 </style>
 
 	</head>