Rename fractional gate tutorial

[nathanearnestnoble]

URL to the relevant tutorial

https://github.com/Qiskit/documentation/blob/main/docs/tutorials/fractional-gates.ipynb.

Select all that apply

• new content request
• typo
• code bug
• out-of-date content
• broken link
• other

Describe the fix or the content request.

Focus of fractional gate tutorial shows the use of these gates in the context of Quantum Kernels. Should rename tutorial to better reflect this, and perhaps consider moving some of the material within into documentation.

For new content requests - if the request is accepted, do you want to write the content?

I will write (or already have written) a draft of the proposed content