Documentation bug fixes: Added procedure to disable built-in Issues.

doc/user/project/integrations/redmine.md

 # Redmine Service
 
-To enable the Redmine integration in a project, navigate to the
+1. To enable the Redmine integration in a project, navigate to the
 [Integrations page](project_services.md#accessing-the-project-services), click
 the **Redmine** service, and fill in the required details on the page as described
 in the table below.
 
-| Field | Description |
-| ----- | ----------- |
-| `description`   | A name for the issue tracker (to differentiate between instances, for example) |
-| `project_url`   | The URL to the project in Redmine which is being linked to this GitLab project |
-| `issues_url`    | The URL to the issue in Redmine project that is linked to this GitLab project. Note that the `issues_url` requires `:id` in the URL. This ID is used by GitLab as a placeholder to replace the issue number. |
-| `new_issue_url` | This is the URL to create a new issue in Redmine for the project linked to this GitLab project |
+    | Field | Description |
+    | ----- | ----------- |
+    | `description`   | A name for the issue tracker (to differentiate between instances, for example) |
+    | `project_url`   | The URL to the project in Redmine which is being linked to this GitLab project |
+    | `issues_url`    | The URL to the issue in Redmine project that is linked to this GitLab project. Note that the `issues_url` requires `:id` in the URL. This ID is used by GitLab as a placeholder to replace the issue number. |
+    | `new_issue_url` | This is the URL to create a new issue in Redmine for the project linked to this GitLab project |
 
-Once you have configured and enabled Redmine:
+    Once you have configured and enabled Redmine:
+    - the **Issues** link on the GitLab project pages takes you to the appropriate
+      Redmine issue index
+    - clicking **New issue** on the project dashboard creates a new Redmine issue
 
-- the **Issues** link on the GitLab project pages takes you to the appropriate
-  Redmine issue index
-- clicking **New issue** on the project dashboard creates a new Redmine issue
+    As an example, below is a configuration for a project named gitlab-ci.
 
-As an example, below is a configuration for a project named gitlab-ci.
+    ![Redmine configuration](img/redmine_configuration.png)
 
-![Redmine configuration](img/redmine_configuration.png)
+2. To disable the internal issue tracking system in a project, navigate to the General page, expand [Permissions](../settings/index.md#sharing-and-permissions), and slide the Issues switch invalid.
+
+    ![Issue configuration](img/issue_configuration.png)
 
 ## Referencing issues in Redmine