RFC: add information on defaults and UI example.

rfcs/0051-limit-zkapp-cmds-per-block.md

@@ -130,6 +130,17 @@ although it might make it less severe by setting a more fine-grained
 limit. However, considering that it would still be a temporary
 solution, it's probably not worth the effort.
 
+The default would be no limit, as that's the easiest to express.
+Alternatively, we can provide another default, but that would require
+providing an option to disable the limit altogether, complicating the
+interface.
+
+An example call could look like this:
+
+```shell
+$ mina daemon --limit-zkapp-cmds-per-block 64 ...
+```
+
 ## Unresolved questions
 
 Are the drawbacks described in this document an acceptable trade-off