Restore documentation that systemready is obsolete
# OSGi system ready check framework
+Felix System Ready is obsolete and superseded by [Apache Felix Health Checks](https://felix.apache.org/documentation/subprojects/apache-felix-healthchecks.html). Use the out-of-the-box health checks in bundle [org.apache.felix.healthcheck.generalchecks](https://github.com/apache/felix/blob/trunk/healthcheck/README.md#general-purpose-health-checks-available-out-of-the-box).
+
+## Old documentation
+
[![Build Status](https://builds.apache.org/buildStatus/icon?job=Felix%20Systemready)](https://builds.apache.org/job/Felix%20Systemready/)
[![Maven Central](https://maven-badges.herokuapp.com/maven-central/org.apache.felix/org.apache.felix.systemready/badge.svg)](http://search.maven.org/#search%7Cga%7C1%7Cg%3A%22org.apache.felix%22%20a%3A%22org.apache.felix.systemready%22)
