Add sentence to explain both quoted/non-quoted parameters can be registered in media type?

[EskoDijk]

Example:

application/my; param="string1"
application/my; param=string1

We can say the preferred form is unquoted if it is allowed per RFC 9110.
E.g. for absolute URI/URN in parameter values, the quotes would be always needed.

[EskoDijk]

In addition, input from @cabo on the mailing list (2025-01-16) to get a canonical form of registrations:

• preferred form is unquoted (when allowed by RFC 9110)
• semicolon followed by exactly 1 space