Ensure that it's clear how to set voxel sizes with brainreg and brainmapper CLIs

[adamltyson]

We've recently updated our image space definition docs. Our brainreg and brainmapper docs currently link to this page with text such as "You must also specify the orientation and voxel size of your data, see Image definition." However, this page doesn't then tell them to e.g. use the -v flag.

How to actually specify the voxel size should be made clearer in the brainreg and brainmapper docs, along with a note in the image space docs.

[sid-42-d]

Hi @adamltyson ,

I’ve opened PR #424 which clarifies how to specify voxel size (-v, in microns, matching orientation order) and orientation (--orientation) in the brainreg CLI docs, keeping the change limited to the existing hint block.

All checks are passing.

If this approach looks good, I’m happy to apply the same clarification to brainmapper and (if desired) add a small note to the image space definition docs as suggested in the issue. Please let me know how you’d like me to proceed.