documentation for some cycle features is missing

[Natalie]

(just for completeness)
Here: https://bycycle-tools.github.io/bycycle/generated/bycycle.features.compute_features.html

For these ones:

• 'amp_fraction',
• 'amp_consistency',
• 'period_consistency',
• 'monotonicity'

[Ryan Hammonds]

Hi @nschawor, I added documentation for these in #51. I defined these from the bycycle publication. If these definitions look good to you, I can merge and rebuild the site.

[tom]

merged in #51