Propagators API: RFC7230 has been obsoleted by RFC9110 and RFC9112

[hiroyaonoe]

What are you trying to achieve?

RFC7230, which specifies HTTP header fields, has been obsoleted by RFC9110 and RFC9112 in June 2022.

opentelemetry-specification/specification/context/api-propagators.md

Lines 122 to 123 in bc61ad5

	In order to increase compatibility, the key/value pairs MUST only consist of US-ASCII characters
	that make up valid HTTP header fields as per [RFC 7230](https://tools.ietf.org/html/rfc7230#section-3.2).

Shouldn't we update the Propagators API documentation to reference RFC9110 Section 5 (or Section 6.3), which specifies the latest HTTP Header Fields specification?
RFC9110 is a compilation of HTTP specifications since HTTP/2 and HTTP/3 are newly introduced.
Therefore, there are no changes to the HTTP header fields specification, and this issue does not alter the Propagators API specification.

What did you expect to see?

 In order to increase compatibility, the key/value pairs MUST only consist of US-ASCII characters 
 that make up valid HTTP header fields as per [RFC9110](https://tools.ietf.org/html/rfc9110/#name-fields).

Additional context.
Propagators API#TextMap Propagator

[lmolkova]

@hiroyaonoe thank you for reporting this! would you be willing to send to PR to update the RFC link? Thanks!