Update references to openmobilehub.com in documentation and fix broken links

[dzuluaga]

Several references to openmobilehub.com are outdated and need to be updated throughout the repository. The Getting Started documentation, for instance, contains broken links that prevent users from accessing important resources like the sample app setup guide.

Steps to Reproduce:

1. Navigate to the sample app section in the Getting Started guide: https://openmobilehub.github.io/react-native-omh-auth/docs/getting-started/#sample-app
2. The link returns a 404 error, making it difficult for developers to follow the steps to set up the sample app.

Impact:
Developers relying on the documentation will encounter a significant roadblock when trying to set up the sample app, which is a critical part of learning and utilizing the SDK. Without proper guidance, they may not be able to run the sample app, affecting their overall experience with the SDK. This needs to be resolved to ensure a seamless onboarding process.

Expected Outcome:

• Update all references from openmobilehub.com to the correct URLs.
• Ensure the sample app section and other critical parts of the documentation are accessible and provide proper guidance to developers.

Additional Context:
You can find the outdated references using this search: https://github.com/search?q=repo%3Aopenmobilehub%2Freact-native-omh-auth%20www.openmobilehub.com&type=code.

Thanks for addressing this issue to improve the developer experience!