prowler feat(docs): add new docker pull issues section

Context

Users installing Prowler via the Docker pull method often encounter common issues such as authentication errors, network timeouts, or missing image tags. These problems are recurrent and reported across various channels, creating friction in the setup experience.

Adding a dedicated troubleshooting section will help reduce user frustration and support burden by proactively addressing known installation issues, besides this installation method is not officially supported.

Description

This PR introduces a new section to the Prowler documentation under the installation guide titled "Common Issues with Docker Pull Installation".

Checklist

Are there new checks included in this PR? Yes / No
- If so, do we need to update permissions for the provider? Please review this carefully.
[ ] Review if the code is being covered by tests.
[ ] Review if code is being documented following this specification https://github.com/google/styleguide/blob/gh-pages/pyguide.md#38-comments-and-docstrings
[ ] Review if backport is needed.
[ ] Review if is needed to change the Readme.md
[ ] Ensure new entries are added to CHANGELOG.md, if applicable.

API

[ ] Verify if API specs need to be regenerated.
[ ] Check if version updates are required (e.g., specs, Poetry, etc.).
[ ] Ensure new entries are added to CHANGELOG.md, if applicable.

License

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.