Split ALWAYS_PARENT based on default behavior if no parent

Signed-off-by: Bogdan Drutu <[email protected]>

Author: bogdandrutu

specification/trace/sdk.md

@@ -105,11 +105,17 @@ These are the default samplers implemented in the OpenTelemetry SDK:
 
 * ALWAYS_ON
   * This will be used as a default.
+  * Returns `RECORD_AND_SAMPLED` always.
   * Description MUST be `AlwaysOnSampler`.
 * ALWAYS_OFF
+  * Returns `NOT_RECORD` always.
   * Description MUST be `AlwaysOffSampler`.
-* ALWAYS_PARENT
-  * `Returns RECORD_AND_SAMPLED` if `SampledFlag` is set to true on parent
+* ALWAYS_PARENT_OR_ON
+  * Returns `NOT_RECORD` if `SampledFlag` is set to `false` on parent
+  SpanContext and `RECORD_AND_SAMPLED` otherwise.
+  * Description MUST be `AlwaysParentSampler`.
+* ALWAYS_PARENT_OR_OFF
+  * Returns `RECORD_AND_SAMPLED` if `SampledFlag` is set to `true` on parent
   SpanContext and `NOT_RECORD` otherwise.
   * Description MUST be `AlwaysParentSampler`.
 * Probability