Fix librispeech default path to signify auto download

[karthik19967829]

As Librispeech recipe automatically downloads the dataset, adding downloads against the path

[codecov]

Codecov Report

Merging #4517 (31ca8aa) into master (f2778f7) will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master    #4517   +/-   ##
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  Coverage   82.40%   82.40%           
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  Files         481      481           
  Lines       41238    41238           
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  Hits        33982    33982           
  Misses       7256     7256           

Flag	Coverage Δ
test_integration_espnet1	66.38% <ø> (ø)
test_integration_espnet2	49.17% <ø> (ø)
test_python	69.40% <ø> (ø)
test_utils	23.30% <ø> (ø)

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[ftshijt]

Sorry, I do not fully understand why the change is necessary. In my view, Librispeech is relatively large to download, it would be better for users to add their own preferences of the directory in db.sh for memory safety.

[karthik19967829]

Yes that's one view point . I just wanted to indicate a way to indicate that it downloads. As the db.sh header says that all datasets with downloads as path has auto download

[sw005320]

If we strictly follow the rule, @karthik19967829 is right.
I'll merge this PR.
Thanks, @karthik19967829!