You can ignore that docoumentation (it is marked as obsolete), since the Web Client has been removed from Alfresco since version 5.0, so you no longer have anything to customise by the web-client-config-context.xml
Are you using Share by any chance? This you can of course still customise, e.g. add an advanced search form or configure a custom query template.
Thank you for responding, I have created advanced search based on the link which you are mentioned, it's working fine. I want to do a search on a right top corner search box with my custom properties. For that, I modified the custom query template in live-search-docs.get.config.xml and search.get.config.xml and i placed these both files in these path D:\spring tool suite - workspace\alfmodule\alfmodule-repo-amp\src\main\amp\config\alfresco\extension\templates.
But,when i search with the value of the property which i added in cusom query template is not filetering the value.