docs: add missing mustache documentation

templates/package_search/area.mustache

@@ -20,9 +20,20 @@
     Represents a reactive package search area consisting of a searchbar and a package container.
 
     Classes required for JS:
-    * qpy-package-search-search-bar,
+    * qpy-package-search-search-bar
     * qpy-package-search-container
 
+    Data attributes required for JS:
+    * data-for="search-bar"
+    * data-for="all-header"
+    * data-for="recently-used-header"
+    * data-for="favourites-header"
+    * data-for="mine-header"
+    * data-for="all-content"
+    * data-for="recently-used-content"
+    * data-for="favourites-content"
+    * data-for="mine-content"
+
     Example context (json):
     {
         "contextid": 1,