unified_joke_explanations.jsonl does not include <bot> response.

[xuanqing94]

Describe the bug
example:

{"text": "<human>: Why is this joke funny? Q: What does a computer do when it is tired? A: It crashes!
Rosey: Did your computer ever stop working (freeze) or turn itself off when you wanted to use it? If it did, you can say your 
computer crashed. Computer crashes are frustrating because you cannot get your work done, and sometimes you lose the 
work you finished most recently, unless you saved it. Thankfully, they do not happen too often."}

Clearly, we need to replace every "\nRosey:" to "\n<bot>:"

[csris]

Good catch! Moving to the data repo.