Add workflow constructors to `Core Application` section

### Temporal Affiliation

- [x] I am a Temporal employee

### Content Suggestion

We should cover workflow constructors in `Core Application` section, currently we only cover it in [Message Passing](https://docs.temporal.io/develop/java/message-passing#use-workflowinit-to-operate-on-workflow-input-before-any-handler-executes). This needs to be added to all SDKs, but Go and Typescript.