Add storagedemo example from previously removed strategy

docs/storage.rst

@@ -40,16 +40,31 @@ Where ``<AppName>`` is ``dexbot`` and ``<AppAuthor>`` is
 Simple example
 --------------
 
+.. code-block:: python
 
-.. literalinclude:: ../dexbot/strategies/storagedemo.py
-   :language: python
-   :linenos:
+   from dexbot.basestrategy import BaseStrategy
+
+
+   class Strategy(BaseStrategy):
+       """
+       Storage demo strategy
+       Strategy that prints all new blocks in the blockchain
+       """
+
+       def __init__(self, *args, **kwargs):
+           super().__init__(*args, **kwargs)
+           self.ontick += self.tick
+
+       def tick(self, i):
+           print("previous block: %s" % self["block"])
+           print("new block: %s" % i)
+           self["block"] = i
 
 **Example Output:**
 
 ::
 
-  Current Wallet Passphrase: 
+  Current Wallet Passphrase:
   previous block: None
   new block: 008c4c2424e6394ad4bf5a9756ae2ee883b0e049
   previous block: 008c4c2424e6394ad4bf5a9756ae2ee883b0e049