man: add news entry

assets/javascripts/news.json

@@ -1,4 +1,8 @@
 [
+  [
+    "2024-08-20",
+    "New documentation: <a href=\"/man/\">Linux man pages</a>"
+  ],
   [
     "2024-07-28",
     "New documentation: <a href=\"/opengl/\">OpenGL</a>"