ZIP 307: arch.png -> zip-0307-arch.png

Signed-off-by: Daira Hopwood <daira@jacaranda.org>

zip-0307.html

@@ -37,7 +37,7 @@ License: MIT</pre>
                 <li><strong>Light client</strong> that subscribes to the stream from a proxy server and uses that data to update its own view of the chain state. The light client MAY be attached to a wallet backend that will track particular Sapling notes.</li>
             </ul>
             <figure class="align-center" align="center">
-                <img src="arch.png" />
+                <img src="zip-0307-arch.png" />
                 <figcaption>Outline of the light wallet architecture</figcaption>
             </figure>
         </section>

zip-0307.rst

@@ -52,7 +52,7 @@ There are three logical components to a Zcash light client system:
   update its own view of the chain state. The light client MAY be attached to a wallet
   backend that will track particular Sapling notes.
 
-.. figure:: arch.png
+.. figure:: zip-0307-arch.png
     :align: center
     :figclass: align-center