docs: Wrong option to print FIB's content, instead you must provide -b

Change-Id: I8a7330d29bc0749bea06286f1a08f08e0654f056
diff --git a/docs/TOPOLOGY.md b/docs/TOPOLOGY.md
index c542de2..950e2c0 100644
--- a/docs/TOPOLOGY.md
+++ b/docs/TOPOLOGY.md
@@ -181,7 +181,7 @@
 Assuming that all three routers are configured correctly and converged, nfd-status
 in `/ndn/edu/colostate/%C1.Router/router2` will have the following entries for the
 name advertised by `/ndn/edu/memphis/%C1.Router/router1`. This output can be 
-seen by typing `nfd-status -f` in terminal
+seen by typing `nfd-status -b` in terminal
 
 FIB: