Adding biobjective example Raytune/Nevergrad

[peter-b-k]

Adding a biobjective example on the usage of Nevergrad to solve a biobjective optimization problem utilising Raytune.

Types of changes

• Docs change / refactoring / dependency upgrade
• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)

Motivation and Context / Related issue

Based on suggestions through the Nevergrad Facebook group, we propose adding an example for the usage of Raytune with Nevergrad for solving a biobjective optimization problem.

How Has This Been Tested (if it applies)

The example executes on test data successfully.

Checklist

• The documentation is up-to-date with the changes I made.
• I have read the CONTRIBUTING document and completed the CLA (see CLA).
• All tests passed, and additional code has been covered with new tests.