Fix docs YAML templates section contents

[yousefmoazzam]

Not sure what exactly should be there, but in a section for YAML templates I'm guessing that API docs for httomo loaders and the other modules/python files with "load" in the name shouldn't be there: https://raw.githubusercontent.com/DiamondLightSource/httomo/136efb4d17244d21f27122941ba2c6f634b2f310/docs/source/backends/templates.rst

See the "HTTomo" section in the screenshot below to see what this produces in the docs build:

[yousefmoazzam]

Ok, a comparison to the last deployment of the docs https://diamondlightsource.github.io/httomo/reference/templates.html (which I'm assuming had something more sensible than what is there currently) shows that this should just have:

• links to each module within the listed backends (ie, httomolibgpu.misc.corr within httomolibgpu)
• where there are dropdowns containing the YAML template for each method within the module (ie, YAML templates for all methods within the httomolibgpu.misc.corr module)

so something definitely doesn't look quite right for this entire page.