Document MDC propagation library.

Author: sjoerdtalsma

mdc-propagation/README.md

@@ -0,0 +1,31 @@
+[![Released Version][maven-img]][maven] 
+
+# Slf4J MDC propagation library
+
+Adding the `mdc-propagation` jar to your classpath
+is all that is needed to automatically let the [MDC] 
+from [Slf4J] become part of the `ContextSnapshot`.
+
+## How to use this library
+
+Add it to your classpath. 
+```xml
+<dependency>
+    <groupId>nl.talsmasoftware.context</groupId>
+    <artifactId>mdc-propagation</artifactId>
+    <version>[see maven-central version above]</version>
+</dependency>
+```
+
+Done!
+
+Now the `MDC.getCopyOfContextMap()` is propagated into each
+snapshot created by the `ContextManagers.createSnapshot()` method.
+This includes all usages of the `ContextAwareExecutorService`.
+
+
+  [maven-img]: https://img.shields.io/maven-central/v/nl.talsmasoftware.context/mdc-propagation.svg
+  [maven]: http://search.maven.org/#search%7Cga%7C1%7Cg%3A%22nl.talsmasoftware.context%22%20AND%20a%3A%22mdc-propagation%22
+
+  [slf4j]: https://www.slf4j.org/
+  [mdc]: https://www.slf4j.org/api/org/slf4j/MDC.html

opentracing-span-propagation/README.md

@@ -21,7 +21,8 @@ Add it to your classpath.
 Done!
 
 Now the `GlobalTracer.getActiveSpan()` is propagated into each
-background thread you start with the `ContextAwareExecutorService`.
+snapshot created by the `ContextManagers.createSnapshot()` method.
+This includes all usages of the `ContextAwareExecutorService`.
 
 
   [maven-img]: https://img.shields.io/maven-central/v/nl.talsmasoftware.context/opentracing-span-propagation.svg