I have read Helm chart to use secrets from cert-manager, but the answer eludes me...

Does

... write the YAML for the Certificate in the same chart, typically in its own file.

just mean that I create a file inside my helm chart templates folder with the name "Certificate.yaml" with the yaml and helm autodiscovers it?

values.yaml:

replicaCount: 1

image:
  repository: nginx
  pullPolicy: IfNotPresent
  tag: ""

imagePullSecrets: []
nameOverride: "sample-app"
fullnameOverride: "sampleapp-chart"

serviceAccount:
  create: true
  annotations: {}
  name: "sampleappacc"

podAnnotations: {}

podSecurityContext: {}

securityContext: {}

service:
  type: NodePort
  port: 80

ingress:
  enabled: true
  className: "traefik-internal"
  annotations: 
     traefik-internal
     "true"
     default-redirect-https@kubernetescrd
  hosts:
    - host: sample.k8s.tld
      paths:
        - path: /
          pathType: ImplementationSpecific
  tls: 
    - secretName: sample-tls
      hosts:
        - sample.k8s.tld

resources: {}

autoscaling:
  enabled: false
  minReplicas: 1
  maxReplicas: 100
  targetCPUUtilizationPercentage: 80

nodeSelector: {}

tolerations: []

affinity: {}

Certificate.yaml

apiVersion: 
kind: Certificate
metadata:
  name: {{ (index .Values.ingress.tls 0).secretName }}
  namespace: default
spec:
  # Secret names are always required.
  secretName: {{ (index .Values.ingress.tls 0).secretName }}
  duration: 2160h # 90d
  renewBefore: 360h # 15d
  subject:
    organizations:
      - myorg
  commonName: {{ (index .Values.ingress.hosts 0).host }}
  isCA: false
  privateKey:
    algorithm: RSA
    encoding: PKCS1
    size: 4096
  usages:
    - server auth
    - client auth
  # At least one of a DNS Name, URI, or IP address is required.
  dnsNames:
    - {{ (index .Values.ingress.hosts 0).host }}
  issuerRef:
    name: letsencrypt-prod
    kind: ClusterIssuer
    group: cert-manager.io

How do I tell helm to read this file?

Running kubectl get certificate results in No resources found in default namespace.
Running kubectl get certificate -A shows some certificates, but not the one I am expecting. Running kubectl get secret shows me only a secret named sh.helm.release.v1.sampleapp-chart.v1 not sample-tls

Update

I found a warning entitled "BadConfig" from cert-manager-ingress-shim with an issue regarding the Issuer. Since I do have the issuer defined in the Certificate.yaml I assume that cert-manager is trying to guess the details from the bare configuration?