tcllib: add news entry

assets/javascripts/news.json

@@ -1,4 +1,8 @@
 [
+  [
+    "2025-07-14",
+    "New documentation: <a href=\"/tcllib/\">Tcllib</a>"
+  ],
   [
     "2025-06-27",
     "New documentation: <a href=\"/zsh/\">Zsh</a>"