When visiting an issue it is possible to be shown related KB articles on the right hand side.
To get access to this feature there are two main steps to follow, Giving a certain user roll permission to make this setting and making the setting.
1. Go to General - Setting - Roles/Groups - Role permission
2. In Issues/Task check the box for 'Show related item auto suggest' for the roles that should have access to make this setting in Issue settings.
3. Every change you do on this page is immediate but you need to logout and then login again for changes to take effect.
4. When logged in again go to Project - Settings - General issue settings
5. Check the box for 'Automatic suggestion of related items' and press Save.
By doing this you will be able to see relared KB articles easily on the right side. The match is done based upon the content in the title as well as the product / service that you have selested. See below for an example