Merge branch 'docs-jira-service-api' into 'master'

Document active param for JIRA service API

See merge request gitlab-org/gitlab-ce!25282

doc/api/services.md

@@ -522,6 +522,7 @@ Parameters:
 | `project_key`   | string | yes | The short identifier for your JIRA project, all uppercase, e.g., `PROJ`. |
 | `username`      | string | yes  | The username of the user created to be used with GitLab/JIRA. |
 | `password`      | string | yes  | The password of the user created to be used with GitLab/JIRA. |
+| `active`        | boolean | no  | Activates or deactivates the service. Defaults to false (deactivated). |
 | `jira_issue_transition_id` | integer | no | The ID of a transition that moves issues to a closed state. You can find this number under the JIRA workflow administration (**Administration > Issues > Workflows**) by selecting **View** under **Operations** of the desired workflow of your project. The ID of each state can be found inside the parenthesis of each transition name under the **Transitions (id)** column ([see screenshot][trans]). By default, this ID is set to `2`. |
 
 ### Delete JIRA service