fix(docs): add disclaimer about parsing set-cookie

[wesleytodd]

This is a common ask. Maybe this type of disclaimer might help?

[blakeembrey]

Suggested change

	**NOTE:** This method does not parse the `set-cookie` header. It parses the `cookie` header. This means you cannot do `cookie.parse(cookie.serialize('name', 'value'))`.
	**Note:** This method does not parse the `Set-Cookie` header.

It already says it parses the Cookie header twice in the above paragraph, would prefer to keep the note shorter so someone skimming actually reads it.

[jonchurch]

lmao I went in the opposite direction with my suggestion.

[jonchurch]

I'd split the difference

⚠️ Note: This method does not parse the Set-Cookie header.

[wesleytodd]

I am personally in favor of a more detailed description. Honestly I would prefer to talk about the difference and even show a detailed example (on top of what your suggestion is below). The larger we make the block warning for this the more likely someone is to see it IMO. Replying here since this is the one with the discussion, but I lean toward @jonchurch's direction below.

[jonchurch]

The example can be improved, as that code works fine.

serialize w/ no options essentially makes a valid Cookie string as it just sets the cookie name and value.
The real trouble is when folks use the options. Specifically the flag options like HttpOnly, Secure, Partitioned which aren't key value pairs like a cookie header.

I think we should give folks a little more info so they understand the failure state and risk.

[jonchurch]

Suggested change

	**NOTE:** This method does not parse the `set-cookie` header. It parses the `cookie` header. This means you cannot do `cookie.parse(cookie.serialize('name', 'value'))`.
	> ⚠️ **NOTE:** This method does not parse the `set-cookie` header. It parses the `cookie` header. This means you cannot safely parse a `set-cookie` header, or the output of `serialize`.
	>
	> E.g. `cookie.parse(cookie.serialize('name', 'value', { httpOnly: true, secure: true, partitioned: true }))` will drop the `httpOnly, secure, partitioned` values entirely. Parsing `set-cookie` header values will result in unexpected results!