Remove duplicate non-root README files

Normalize dataset README placement

Move selected datasets to Endoscopy continued (24)

Move selected datasets to Endoscopy continued (23)

Move selected datasets to Endoscopy continued (22)

Move selected datasets to Endoscopy continued (21)

Move selected datasets to Endoscopy continued (20)

Move selected datasets to Endoscopy continued (19)

Move selected datasets to Endoscopy continued (18)

Move selected datasets to Endoscopy continued (17)

Move selected datasets to Endoscopy continued (16)