Add documentation for Managed Identity v2 Hackathon (#885)

* Add documentation for Managed Identity v2 Hackathon

Document the results and outcomes of the Managed Identity v2 Multi-Language Implementation Hackathon, highlighting the achievements and deliverables.

* Apply suggestions from code review

Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>

* Update spikes/prototype/2026_MS_SecurityHackathon_MSIV2.md

Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>

---------

Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>

Author: gladjohn