Add "description" key to opendistro-security tenant create call

[KorvinSzanto]

Add description json body key to opendistro-security tenant create call used in the sync:opendistro-security command

Checklist

• Affected Issues have been mentioned in the Closing issues section
• Documentation has been written/updated
• PR title is ready for changelog and subsystem label(s) applied

Opendistro-security's API endpoint for creating tenants has been updated (I couldn't find the change, maybe someone else can?) to require a description so this PR updates our API call to include a generic description.

Closing issues

closes #2577

[Schnitzel]

superseeded by #2772
@tobybellwood can we make sure we give @KorvinSzanto credits on the release notes as he found it first? Thanks!

[tobybellwood]

Yup! Sorry I forgot about this PR!