Put fgraph and conditioning model transforms inside model header in API Docs

[ricardoV94]

These last two entries should be listed inside the Model entry.

change_value_transforms and remove_value_transforms should show in the sub-header as well:

And not only under Others:

Also the rendering of these code examples seems broken:

https://www.pymc.io/projects/docs/en/v5.8.2/api/model/transform/generated/pymc.model.transform.conditioning.change_value_transforms.html

https://www.pymc.io/projects/docs/en/v5.8.2/api/model/transform/generated/pymc.model.transform.conditioning.remove_value_transforms.html