Document task sdk versioning and how it affects runtime behaviour

[uranusjr]

Body

See devlist https://lists.apache.org/thread/wx5gjxq9rm0tkw4d2dczfmcdkn7dd6xd

Committer

• I acknowledge that I am a maintainer/committer of the Apache Airflow project.

[KoviAnusha]

@jscheffl @uranusjr @amoghrajesh @potiuk @kaxil can I work on this issue? If so, could you please assign this to me?

[Ratasa143]

Hi, I’d like to work on this.
Before I start, could you clarify where you’d prefer this to be documented and what specific runtime behaviors around Task SDK versioning should be covered?
Happy to put up a small, focused docs PR once that’s clear. Thanks