docs: improve backend README with Kubernetes setup, troubleshooting, and fixes. (#1782)

Signed-off-by: Pranali Deshmukh <pranali.deshmukh@swirldslabs.com>
Signed-off-by: John Bair <117694970+jbair06@users.noreply.github.com>
Co-authored-by: John Bair <117694970+jbair06@users.noreply.github.com>

Author: deshmukhpranali