Correct casing typo.

The script here refers to "Alice-sentences.txt" but the name of the file in the repo is "Alice-Sentences.txt". This works if the files are being served from a case-insensitive filesystem (for example, the default Mac OS X filesystem), but will cause the request to 404 when the files are being served from a case-sensitive filesystem. This typo corrects the issue by changing the request. Alternatively, consider lowercasing the name of the text file to avoid potential filesystem case-sensitivity issues in the future.