Add docs about context and coroutines integration

Author: rocketraman

src/site/index.adoc

@@ -138,6 +138,26 @@ assert(message == ContextStack.pop())
 assert(ContextStack.empty)
 ----
 
+A `CoroutineThreadContext` context element is provided to integrate logging context with coroutines.
+
+[source,kotlin]
+----
+launch(loggingContext(mapOf("myKey" to "myValue"), listOf("test"))) {
+  assertEquals("myValue", ContextMap["myKey"])
+  assertEquals("test", ContextStack.peek())
+}
+----
+
+or to preserve the existing context:
+
+[source,kotlin]
+----
+launch(additionalLoggingContext(mapOf("myKey" to "myValue"), listOf("test"))) {
+  assertEquals("myValue", ContextMap["myKey"])
+  assertEquals("test", ContextStack.peek())
+}
+----
+
 [#params]
 == Parameter substitution