Fix formatting of CLI encoding

[orome]

The behavior of encode does not match the documentation:

• the -f flag is not recognized, and
• output is broken into blocks of 4 by default (as if -f had been provided).

To fix:

• [x] first change documentation and cli hep to match behavior, then
• [ ] implement a flag for formatting in blocks of 4 and make unblocked the default.

[orome]

Documentation fixed in bddc0fc1.