Add the doc for new schema compatibility strategy.

[congbobo184]

link #5227 , add the new schema compatibility strategy doc for 2.5.0 version in pulsar.

[Jennifer88huang-zz]

When you add docs for this feature, feel free to ping us.

[sijie]

@jennifer88huang @congbobo184 can you please add the documentation for 2.5.0 features. It is a blocker for 2.5.0 release.

[Jennifer88huang-zz]

Got it.

[Anonymitaet]

I'm handling this task and @congbobo184 will provide technical inputs.