Add DPG Badge

[BolajiAyodeji]

Description

This PR includes the new DPG badge to the README file following the guide and links to OpenFn's new profile page URL on the DPG Registry.

Validation steps

1. Preview the README changes on the head repository.
2. Verify the right markdown usage.

Additional notes for the reviewer

N/A

AI Usage

Please disclose how you've used AI in this work (it's cool, we just want to know!):

• Code generation (copilot but not intellisense)
• Learning or fact checking
• Strategy / design
• Optimisation / refactoring
• Translation / spellchecking / doc gen
• Other
• I have not used AI

You can read more details in our Responsible AI Policy

Pre-submission checklist

• I have performed a self-review of my code.
• I have implemented and tested all related authorization policies. (e.g., :owner, :admin, :editor, :viewer)
• I have updated the changelog.
• I have ticked a box in "AI usage" in this PR

[josephjclark]

Thank you @BolajiAyodeji this is awesome!

Most of the team is away until the new year, but they'll be thrilled to get this merged in once they're back online

[taylordowns2000]

thanks @BolajiAyodeji ! looks great :-)