docs: correct match selector section in auto app discovery guide

[prospero238]

Summary

The observability guide here includes deployment manifests whose selector.matchLabels does not match the template's metadata.labels. This results in an error when trying to apply the manifest.

Specifically, the error is:

Error from server (Invalid): error when creating "sample-deployment.yaml": Deployment.apps "podtato-head-frontend" is invalid: spec.template.metadata.labels: Invalid value: map[string]string{"app.kubernetes.io/name":"podtato-head-frontend", "app.kubernetes.io/part-of":"podtato-head", "app.kubernetes.io/version":"0.1.0"}: `selector` does not match template `labels`
Error from server (Invalid): error when creating "sample-deployment.yaml": Deployment.apps "podtato-head-hat" is invalid: spec.template.metadata.labels: Invalid value: map[string]string{"app.kubernetes.io/name":"podtato-head-hat", "app.kubernetes.io/part-of":"podtato-head", "app.kubernetes.io/version":"0.1.1"}: `selector` does not match template `labels`

To test, I applied the revised manifests to my cluster and observed that there were no errors, and the desired deployments were created.

Please let me know if there's anything else I need to do to fulfill PR requirements.

Checks

• My PR fulfills the Definition of Done of the corresponding issue and not more (or parts if the issue is separated
  into multiple PRs)
• I used descriptive commit messages to help reviewers understand my thought process
• I signed off all my commits according to the Developer Certificate of Origin (DCO)(
  see Contribution Guide)
• My PR title is formatted according to the semantic PR conventions described in
  the Contribution Guide
• My content follows the style guidelines of this project (YAMLLint, markdown-lint)
• I regenerated the auto-generated docs for Helm and the CRD documentation (if applicable)
• I have performed a self-review of my content including grammar and typo errors and also checked the rendered page
  from the Netlify deploy preview
• My changes result in all-green PR checks (first-time contributors need to ask a maintainer to approve their test runs)

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud

[mowies]

LGTM