Remove the need to maintain third party propagators. (open-telemetry#…

…1144)

* Remove the need to mantain third party propagators.

* Update the docs to be more liberal.

* Update specification/context/api-propagators.md

Co-authored-by: Yuri Shkuro <[email protected]>

* Update specification/context/api-propagators.md

Co-authored-by: (Eliseo) Nathaniel Ruiz Nowell <[email protected]>

* Remove the mention of XRay propagator.

Co-authored-by: Yuri Shkuro <[email protected]>
Co-authored-by: (Eliseo) Nathaniel Ruiz Nowell <[email protected]>

specification/context/api-propagators.md

@@ -320,19 +320,8 @@ organization and MUST be distributed as OpenTelemetry extension packages:
 * [Jaeger](https://www.jaegertracing.io/docs/latest/client-libraries/#propagation-format).
 
 Additional `Propagator`s implementing vendor-specific protocols such as AWS
-X-Ray (Note, AWS is used as an example, not as a requirement) trace header
-protocol can be either maintained and distributed by their respective vendors or
-as part of the OpenTelemetry organization. The reasons for maintaining those as
-a community are:
-
-- Propagators are small pieces of code and their functionality is often publicly
-  documented (unlike exporters).
-- People will often need to use propagators that are not specific to their
-  tracing or metrics vendor. For example, customers of tracing vendor may still
-  want to use an Cloud vendor-specific propagator for requests to the services
-  of this cloud vendor.
-- Only a small number of propagators will need to exist, and this number will
-  shrink as vendors and users shift to W3C TraceContext.
+X-Ray trace header protocol MUST NOT be maintained or distributed as part of
+the Core OpenTelemetry repositories.
 
 ### B3 Requirements