add info to readme about CLI options

[wdduncan]

It would be helpful (at least for me) if the README had info about the CLI options (.e.g., non-redundant-output-file, redundant-output-file). The relation-graph --help is a bit terse:

Config
Usage: config [options]
  --usage  <bool>
        Print usage and exit
  --help | -h  <bool>
        Print help message and exit
  --ontology-file  <string>
  --non-redundant-output-file  <string>
  --redundant-output-file  <string>
  --mode  <output mode>
  --property  <string*>
  --properties-file  <string?>
  --output-subclasses  <boolean value>
  --reflexive-subclasses  <boolean value>
  --equivalence-as-subclass  <boolean value>

[balhoff]

I agree!