Add guidance for linking realm to local examples

[takameyer]

What, How & Why?

Our previous example was already updated to link to realm. We have since come up with even more examples and decided to keep them pure so that they are easier to use and also easier to update to newer version of React Native.

However, to debug using these examples requires some extra steps. I had tried to create a generic patch to do this, but it proved to be more trouble than it's worth. I have since created a guide to manually do this ourselves.

☑️ ToDos

• 📝 Changelog entry
• 📝 Compatibility label is updated or copied from previous entry
• 📝 Update COMPATIBILITY.md
• 🚦 Tests
• 📦 Updated internal package version in consuming package.jsons (if updating internal packages)
• 📱 Check the React Native/other sample apps work if necessary
• 💥 Breaking label has been applied or is not necessary

[coveralls-official]

coverage: 85.397%. remained the same when pulling 0bfb33c on andrew/link-realm-guide into eca95b6 on main.

[kneth]

We need to put our users first at the expense of our development experience

[elle-j]

Good guide, thank you! Only got some minor suggestions.