PR #165 and #166, correction in contrib examples

[iArpanPatel]

• Example contribution PR "added Cataract detection #165" with corrections needed to run the example.
• Example contribution PR "Added nail-disease to examples #166" with corrections needed to run the example.
• Workaround for failure in installing Swarm Learning whl file.
• Existing example contribution documentation correction.

[iArpanPatel]

cataract-sl1.txt cataract-sl2.txt cataract-ml1.txt cataract-ml2.txt nail-sl1.txt nail-sl2.txt nail-ml1.txt nail-ml2.txt