docs: add spatial standards to Contribute documentation

[jahilton]

This page should reflect an overview of the submission requirements, but has yet to be updated to reflect Visium & Slide-seq requirements.

[github-actions]

Deployment Summary

• backend_url: https://pr-7367-backend.rdev.single-cell.czi.technology
• backend_de_url: https://pr-7367-backend-de.rdev.single-cell.czi.technology
• backend_wmg_url: https://pr-7367-backend-wmg.rdev.single-cell.czi.technology
• frontend_url: https://pr-7367-frontend.rdev.single-cell.czi.technology
• delete_db_task_definition_arn: arn:aws:ecs:us-west-2:***:task-definition/dp-rdev-pr-7367-deletion:1
• migrate_db_task_definition_arn: arn:aws:ecs:us-west-2:***:task-definition/dp-rdev-pr-7367-migration:1

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 92.90%. Comparing base (9c87d94) to head (00d9b15).

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #7367   +/-   ##
=======================================
  Coverage   92.90%   92.90%           
=======================================
  Files         194      194           
  Lines       16831    16831           
=======================================
  Hits        15637    15637           
  Misses       1194     1194           

Flag	Coverage Δ
unittests	92.90% <ø> (ø)

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[MaximilianLombardo]

lgtm!