Issue #2945386 by Erik de Kamps, Lendude, Anybody: Add configure link to the module on the 'extend' page

Issue #3019197 by alonaoneill, Aanal.addweb, Anybody: Capitalize the name of the module in .info.yml file

Issue #3135797 by karishmaamin, gun2dru, nikolas.tatianenko, Anybody: Drupal 9 deprecated code report

added a function which retrieves the excluded node ids + node titles and put some form text into t function

removed IF block, which became obsolete, when I changed the variable format of the exclusion nid list from string to array.

changes css id of node list items to something more specific, added some more comments, changes unnecessary transformation of $nid var as we already loaded a node object

added restrict access => permission, to make clear that this permission is thought only to be added to site administrators

added admin.inc file to get form stuff out of the module + refactored how variable is stored. node ids are now added as an array, instead as a string, so we dont have to explode them every time we manipulate or alter a search string