SLING-7167 Adjust READMEs

add uniform header linking to Sling project

git-svn-id: https://svn.apache.org/repos/asf/sling/trunk@1810903 13f79535-47bb-0310-9956-ffa450edef68
diff --git a/README.md b/README.md
index ff124f1..67e86e1 100644
--- a/README.md
+++ b/README.md
@@ -1,5 +1,6 @@
-Apache Sling MDC Inserting Filter
-================================
+# Apache Sling SLF4J MDC Filter
+
+This module is part of the [Apache Sling](https://sling.apache.org) project.
 
 This filter exposes various request details as part of [MDC][1].