add gathering-facts example

docsite/latest/rst/examples.rst

@@ -213,6 +213,16 @@ the remote nodes will be terminated.
 Typically you'll be only be backgrounding long-running
 shell commands or software upgrades only.  Backgrounding the copy module does not do a background file transfer.  :doc:`playbooks` also support polling, and have a simplified syntax for this.
 
+Gathering Facts
+```````````````
+
+For each system facts are gathered. These can be used to implement conditional execution of tasks but also just to get ad-hoc information about your system. You can see all facts via:
+
+ $ ansible all -m setup
+
+Its also possible to filter via and export the facts, see the "setup" module documentation for details how to do that.
+
+
 Limiting Selected Hosts
 ```````````````````````