Fix typo in rouge types

[davebulaval]

Minor typo fix in the code and doc example that does not align with the writing style (rougeLsum -> rougeLSum).

[lvwerra]

The name of the variable inside rouge_score uses a lower-case s (see here):

elif rouge_type == "rougeLsum":

So I think we should leave it as it was. Why did you want to change it?

[davebulaval]

The doc state otherwise. Whatever name you want to use, it is just not uniformized.

"rougeLSum"`: rougeLSum splits text using `"\n"`.

[lvwerra]

Ok I see, then let's go with the lower-case version since that's follows the code.

[davebulaval]

Updated.

P.S. I feel like rouseLsum is an odd writing style (rougeL but you add another word, and now is it rougeLsum (same comments for variable names rouge_Lsum but also rouge_L)), but hey it is your code base.

[lvwerra]

Thanks, this looks good! Note that this is not our convention but the follows the underlying library (rouge_score from Google Research).