SLING-7167 Adjust READMEs

add uniform header linking to Sling project

git-svn-id: https://svn.apache.org/repos/asf/sling/trunk@1810933 13f79535-47bb-0310-9956-ffa450edef68
diff --git a/custom-login-form/README.md b/custom-login-form/README.md
index c3095d2..fd36b79 100644
--- a/custom-login-form/README.md
+++ b/custom-login-form/README.md
@@ -1,3 +1,5 @@
-Apache Sling Custom Login Form Sample
+# Apache Sling Sample Custom Login Form
+
+This module is part of the [Apache Sling](https://sling.apache.org) project.
 
 This bundle provides a sample of a custom login form.