extract-texi-filenames - missing directories

[Phil Holmes]

When make doc is run, it complains about 3 missing directories - 
Documentation/hu/included; Documentation/cs/included and 
Documentation/zh/included.  We could add these to the list of "known missing 
directories" in extract-texi-filename.py, but that would be bad if they were 
created.  Anyone object if I create these as empty directories?

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Phil Holmes