Wrong documentation to add a new component

[TheTrainingBoss]

The docs for Widget development still says that you need to register any new component in the file "render-widget-service.tsx" under the TYPES_MAP object but that has changed and now the file "widget-registry.ts" is the one that needs to get the registration of any new component. Please change the documentation under widget-development.md and keep it current so that new interested developers not get confused and waste a lot of time.

[TheTrainingBoss]