Add a few clone detection papers

[sedflix]

Please fill the [ ] with an x to make sure that you read and followed the checklist

• [x] This addition is about Machine Learning on Code specifically. General links should be added to Awesome Machine Learning instead.
• [x] I have checked that the proposed addition is not already in the awesome list.
• [x] I have signed-off my commits as detailed here.

• [x] The links follow the link template:

  * [Title](URL) - Description.

  or

  * [Title](URL) - Description [Code](link to code).

• [x] The addition is correctly classified as a paper, blog post, talk, software or dataset.

• [x] The commit message must start with a verb (Add …, Deprecate …) and end without a dot. For exemple:

  Deprecate Theano software