Fix example in opus_ubuntu, Add license info
CI seems to fail due to languages incorrectly being flagged as invalid, I guess that's related to the currently-broken bcp47 validation (see #4304)
This PR 
* fixes a typo in the example for the`opus_ubuntu` dataset where it's mistakenly referred to as `ubuntu`
* adds the declared license info for this corpus' origin
* adds an example instance
* updates the data origin type