On `dev`: site homepage updates

[egrace479]

Website homepage (docs/index.md):

• Include links to both Imageomics and ABC collaborative infrastructure: "Imageomics and ABC Code Repositories" and "Imageomics and ABC Organization Pages"
• Is there a desire to edit or remove the collaborative infrastructure diagram?
  • Issue Update Collaborative Infrastructure Diagram #49.
• For the logos, do we want to have a single shared logo? (<Organization> Branding (Logos) or Imageomics-ABC Branding (Logos), could include one of each?)
  • ^ This needs deciding.

[egrace479]

I'm going to use the joint logo:

## `<Ogranization>` Branding (Logos)

Since this is a joint Imageomics and ABC project, we have a special combined logo:

![combined Imageomics and ABC logo](logos/Imageomics_ABC.png){: style="width:75%"}