SLING-7167 Adjust READMEs

add uniform header linking to Sling project

git-svn-id: https://svn.apache.org/repos/asf/sling/trunk@1810846 13f79535-47bb-0310-9956-ffa450edef68
diff --git a/README.md b/README.md
index 33b3b92..2333f82 100644
--- a/README.md
+++ b/README.md
@@ -1 +1,3 @@
-Apache Sling Models API
+# Apache Sling Models API
+
+This module is part of the [Apache Sling](https://sling.apache.org) project.