Moved the format string exercise one port down.

nnamon · nnamon · commit 30677d7205e0 · 2017-01-13T08:34:06.000+08:00
diff --git a/lessons/13_fmt_str/services/echo/dockerrun.sh b/lessons/13_fmt_str/services/echo/dockerrun.sh
@@ -1,3 +1,3 @@
 #!/bin/sh
 
-docker run -dt -p 1904:31337 echoes
+docker run -dt -p 1903:31337 echoes
