README: mention example bot

Signed-off-by: Maxime “pep” Buquet <pep@bouah.net>

README.rst

@@ -27,6 +27,19 @@ Installation
 - PIP: `slixmpp-omemo`
 - Manual: `python3 setup.py install`
 
+Examples
+--------
+
+The repository contains an example bot that contains many comments, and
+can be used to test against other setups. To use it:
+
+```
+python examples/echo_bot.py --debug -j foo@bar -p passwd --data-dir /foo/bar
+```
+
+It also contains commands. Feel free to open merge requests or issues to
+add new useful ones.
+
 Credits
 -------