message: Fix typo on Backstage Helm Chart README
diff: | app.resources | Kubernetes Pod resource requests/limits | `{}` |
  | app.nodeSelector | Node selectors for scheduling app/frontend pods | `{}` |
  | app.tolerations | Tolerations for scheduling app/frontend pods | `{}` |
  -| app.affinity | Affinity setttings for scheduling app/frontend pods | `{}` |
  +| app.affinity | Affinity settings for scheduling app/frontend pods | `{}` |
  ## Backend Values
  | backend.resources | Kubernetes Pod resource requests/limits | `{}` |
  | backend.nodeSelector | Node selectors for scheduling backend pods | `{}` |
  | backend.tolerations | Tolerations for scheduling backend pods | `{}` |
  -| backend.affinity | Affinity setttings for scheduling backend pods | `{}` |
  +| backend.affinity | Affinity settings for scheduling backend pods | `{}` |
  