Clarify support status of sle micro in salt ssh context

[admd]

Description

Currently only regular minions are supported when it comes to SLE Micro, it was mentioned in released notes but making it clear in documentation as well

Target branches

• Which product version this PR applies to (Uyuni, SUMA 4.3, SUMA 5.0).

Backport targets (edit as needed):

• master
• 4.3

Links

• This PR tracks issue #<insert spacewalk issue, if any>
• Related development PR #<insert PR link, if any>

[admd]

thank you @keichwa .

@vzhestkov would it suffice or do you want me to expand it further?