Backticks around parameter names

[MikeBishop]

We're somewhat inconsistent about whether transport parameters et al. get backticks or not across the documents. For example,

the ACK Delay field is scaled by multiplying the encoded value by 2 to the
power of the value of the ack_delay_exponent transport parameter set by the
sender of the ACK frame; see {{transport-parameter-definitions}}. Scaling in

The Retire Prior To field counts connection IDs established during connection
setup and the preferred_address transport parameter; see {{retiring-cids}}. The
Retire Prior To field MUST be less than or equal to the Sequence Number field.

Same goes for error code names, frame types, etc.

[martinthomson]

I think that - at this point - the overwhelming majority of parameter names are not quoted in any way and do go in and add backticks to all of them would be tiresome. However, most are in snake_case, CamelCase, Title Case, or SHOUTING_CASE so they are almost always distinguishable anyway.

I grepped through and we have 38 instances of backticks. Most of these are in -http and -qpack. Most of them are in the description of reserved codepoints. I'm going to suggest we remove the others.