Missing JIRA Cloud usage on JIRA plugins page

## Describe the bug
There is no differentiation on the usage if you are using JIRA on prem or cloud.

JIRA on prem you can use:
`login: username`
`password: password`

But on JIRA cloud, you have to use:
`login: email address`
`password: API Token`
 
## Source page
https://docs.rundeck.com/docs/manual/plugins/jira-plugins-overview.html