change file-is-generated doc comment to inner

[hkBst]

Alternatively this could be better as a normal comment...

[rustbot]

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[rustbot]

library/core/src/unicode/unicode_data.rs is generated by the src/tools/unicode-table-generator tool.

If you want to modify unicode_data.rs, please modify the tool then regenerate the library source file via ./x run src/tools/unicode-table-generator instead of editing unicode_data.rs manually.