Documentation of the embedded feedback widget

The ThinkFeedback architecture page now documents the embedded widget: where it appears, which services are deliberately excluded and why, the properties that make one snippet safe to run on every origin, and the fact that widget posts are anonymous.

Until now the widget's deployment was recorded nowhere — it existed only as a setting pasted inside two running services.

Page: https://docs.thinkhead.org/en/Collaboration/thinkfeedback/architecture