ipfs-cap2fs: fix hop count for Kademlia example (fixes ipfs#9)

Since 2**23 doesn't completely cover 10 million nodes, I went for 2**20 which
covers 1 million nodes (as suggested by @RichardLitt).

License: MIT
Signed-off-by: Ivan Vilata-i-Balaguer <[email protected]>

Author: ivilata

ipfs-cap2pfs/ipfs-cap2pfs.tex

@@ -63,7 +63,7 @@ \subsubsection{Kademlia DHT}
 
   \item Efficient lookup through massive networks:
         queries on average contact $ \ceil{log_2 (n)} $ nodes
-        (e.g. $20$ hops for a network of $10,000,000$ nodes).
+        (e.g. $20$ hops for a network of $1,000,000$ nodes).
 
   \item Low coordination overhead: it optimizes the number of
         control messages it sends to other nodes.