[TASK] Improve indexed_search manual

Improves indexed search documentation, mentioning activation
and inclusion of a static template.

Releases: master, 9.5
Resolves: #87023
Change-Id: I85e40b768e4020e71a7717d877a6305fb55a00cb
Reviewed-on: https://review.typo3.org/58968
Tested-by: TYPO3com <noreply@typo3.com>
Reviewed-by: Joerg Kummer <typo3@enobe.de>
Reviewed-by: Josef Glatz <josef.glatz@typo3.org>
Tested-by: Josef Glatz <josef.glatz@typo3.org>
Reviewed-by: Richard Haeser <richard@maxserv.com>
Tested-by: Richard Haeser <richard@maxserv.com>
Reviewed-by: Tymoteusz Motylewski <t.motylewski@gmail.com>
Tested-by: Tymoteusz Motylewski <t.motylewski@gmail.com>

typo3/sysext/indexed_search/Documentation/UserManual/Index.rst

@@ -17,14 +17,16 @@ User manual
 
 Adding the search plugin to a page
 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+#. Activate "indexed_search" in the Extensions Manager. You just need to activate it. It is already
+   installed in non-composer mode. Make sure to require the package `typo3/cms-indexed-search` if
+   you run the TYPO3 instance in composer mode.
 
-That is really easy:
+#. Create a page called "Search" or something like that. This is where the search box will appear.
 
-#. Create a page called "Search" or something like that. This is where
-   the search box will appear.
+#. Create an extension template for this page that includes "Indexed Search (Extbase & Fluid)" or
+   include it in your main template.
 
-#. Create a new content element on that page and choose the type
-   "General Plugin".
+#. Create a new content element on that page and choose the type "General Plugin".
 
 #. Then choose the "Selected plugin" to be "Indexed search":