docs: move technical documentation to TF-Minecraft/docs (#51)

Author: ryanbarlow97

README.md

@@ -0,0 +1,7 @@
+# activity-tf
+
+Technical documentation is maintained in [TF-Minecraft/docs](https://github.com/TF-Minecraft/docs/tree/main/projects/activity-tf).
+
+Use that project index for setup, configuration, architecture, integration and testing guides. This repository contains the source and project-specific assets.
+
+This repository remains private. Public documentation links do not grant access to its contents.