Types of changes

Motivation and context / Related issue

In ot.gromov, I propose minor changes in the docstring:

• Changing "conjugate gradient" to "conditional gradient"
• Making the mathematical notation consistent in gromov_wasserstein and gromov_wasserstein2 by changing from \gamma to T for the transportation plan in the constraints.
  Thank you for your consideration!

How has this been tested (if it applies)

PR checklist

• I have read the CONTRIBUTING document.
• The documentation is up-to-date with the changes I made (check build artifacts).
• All tests passed, and additional code has been covered with new tests.
• I have added the PR and Issue fix to the RELEASES.md file.