Merge branch 'doc_api_services_jira_amend' into 'master'

Amend jira service api docs [ci skip]

## What does this MR do?

Amends the API documentation for jira service integration

## Are there points in the code the reviewer needs to double check?

No

## Why was this MR needed?

The current documentation omits the username and password parameters

## What are the relevant issue numbers?

## Screenshots (if relevant)

See merge request !4382

doc/api/services.md

@@ -503,6 +503,8 @@ Parameters:
 - `project_url` (**required**) - Project url
 - `issues_url` (**required**) - Issue url
 - `description` (optional) - Jira issue tracker
+- `username` (optional) - Jira username
+- `password` (optional) - Jira password
 
 ### Delete JIRA service