Change code example from Implements to Extends

[warrenbuckley]

Description

What did you add/update/change?

A code sample for the UFM component example, using implements means I needed to do more than what I needed to do.
Looked at the source code of the existing UFM-Components and they use the extends approach instead so we only need to implement the render method

Type of suggestion

• Typo/grammar fix
• Updated outdated content
• New content
• Updates related to a new version
• Other

Product & version (if relevant)

Deadline (if relevant)

When should the content be published?

[sofietoft]

Thanks @warrenbuckley !
This makes a lot of sense 💪

Let's get it merged!