Document Lifecycle support

This closes #73

org.eclipse.sisu.inject/src/site/markdown/lifecycle.md

@@ -0,0 +1,14 @@
+# Lifecycle Support
+
+Each Sisu managed bean/component may optionally use annotations on methods to be called whenever the bean is started or stopped.
+
+Those are
+
+Annotation | Method called... | Leveraged Guice Hook
+--- | ---
+ `org.eclipse.sisu.PostConstruct` (or `javax.annotation.PostConstruct`) | Before bean is started | [`com.google.inject.spi.InjectionListener.afterInjection(...)`](https://google.github.io/guice/api-docs/6.0.0/javadoc/com/google/inject/spi/InjectionListener.html#afterInjection(I))
+ `org.eclipse.sisu.PreDestroy` (or `javax.annotation.PreDestroy.`) | Before bean is stopped | Is not called by default, only via [Plexus API](../org.eclipse.sisu.plexus).
+
+ The annotations defined in [JSR 250](https://jcp.org/en/jsr/detail?id=250) are recognized in addition to the native Sisu ones when their classes are detected in the class path.
+
+ The support needs to be explicitly enabled by passing an instance of [`org.eclipse.sisu.bean.LifecycleModule`](apidocs/org/eclipse/sisu/bean/LifecycleModule.html) when creating the `Injector`.

org.eclipse.sisu.inject/src/site/site.xml

@@ -14,6 +14,7 @@
     <menu name="Overview">
       <item name="Introduction" href="index.html"/>
       <item name="Named Index" href="named-index.html"/>
+      <item name="Lifecycle Support" href="lifecycle.html"/>
     </menu>
   </body>
 </site>

org.eclipse.sisu.plexus/src/site/markdown/conversion-to-jsr330.md

@@ -458,7 +458,9 @@ public class MyComponent
 
 ### Startable
 
-Support for JSR250 lifecycle annotations is available when enabled for the Plexus wrapper (\[Maven 3.5+\](https://issues.apache.org/jira/browse/MNG-6084) enables JSR250 support). If JSR250 support is not enabled then applications can use other techniques to handle start/stop behavior. The examples below show the solution used in Sonatype Nexus, which relies on a modified implementation of the Google-Guava EventBus to manage lifecycle events.
+Support for [Sisu/JSR250 lifecycle annotations](../org.eclipse.sisu.inject/lifecycle.html) is available when enabled for the Plexus wrapper (\[Maven 3.5+\](https://issues.apache.org/jira/browse/MNG-6084) enables JSR250 support). 
+
+If JSR250 support is not enabled then applications can use other techniques to handle start/stop behavior. The examples below show the solution used in Sonatype Nexus, which relies on a modified implementation of the Google-Guava EventBus to manage lifecycle events.
 
 ```
 @Component(role=Component.class, hint="my")