SimpleChatTC:IndexHTML:Fix a oversight with new module added

Add forgotten to add , after simplechat entry.

Currently I am not strictly using the importmap feature, so the
error didnt create any problem, but the error was there which has
been fixed.

tools/server/public_simplechat/index.html

@@ -11,7 +11,7 @@
         <script type="importmap">
             {
                 "imports": {
-                    "simplechat": "./simplechat.js"
+                    "simplechat": "./simplechat.js",
                     "datautils": "./datautils.mjs",
                     "ui": "./ui.mjs"
                 }