resolvectl: clarify IDNA and search path logic in combination with "resolvectl query...

resolvectl: clarify IDNA and search path logic in combination with "resolvectl query --type="

When low-level RR resolution is requested from "resolvectl query" via
"--type=" or "--class=" no search domain logic is applied and no IDNA
translation.

Explain this in detail in the documentation, and also mentions this when
users attempt to resolve single-label names or names with international
characters in the output.

I believe the current behaviour is correct, but it is indeed surprising.
Hence the documentation and output improvement.

Fixes: #11325 #10737