In dokuwiki administration page go to –> Extension manager –> Search and install

In Search Extensions filed enter : indexmenu and install extension IndexMenu Plugin

In Search Extensions filed enter : sidebar and install extension Sidebar Plugin

Go to sidebar page which is https://wiki.acim.cz/doku.php?id=sidebar and edit this page.

Add these lines to that page :

{{indexmenu>:|tsort}}
 
~~NOCACHE~~

To add new sidebar item to dokuwiki do this : Create sidebar item : https://wiki.acim.cz/doku.php?id=unix Edit and rename item adding header : Edit item https://wiki.acim.cz/doku.php?id=unix&do=edit