SpanContext.IsRemote is false on remote children (open-telemetry#538)

* SpanContext.IsRemote is false on remote children

The IsRemote flag should be false on children of remote spans,
as the span itself was created locally.

* Update specification/api-tracing.md

Otherwise one could interpret this as "The child span's IsRemote flag must always be false if the parent used to be remote, even after the child was propagated.".

Co-Authored-By: Armin Ruech <armin.ruech@gmail.com>

Co-authored-by: Armin Ruech <armin.ruech@gmail.com>

specification/api-tracing.md

@@ -179,6 +179,7 @@ TraceID and a non-zero SpanID.
 
 `IsRemote` is a boolean flag which returns true if the SpanContext was propagated
 from a remote parent.
+When creating children from remote spans, their IsRemote flag MUST be set to false.
 
 Please review the W3C specification for details on the [Tracestate
 field](https://www.w3.org/TR/trace-context/#tracestate-field).