Explicitly mention Compose as a best practice

PiperOrigin-RevId: 615050775
Change-Id: I4bcd81d46a6e6d14e77dbb69f30d979f582aee6f
diff --git a/docs/principles.md b/docs/principles.md
index 93bc971..689b7ef 100644
--- a/docs/principles.md
+++ b/docs/principles.md
@@ -85,6 +85,9 @@
 
 -   Guide developers toward using existing Jetpack best-practice libraries,
     including Architecture Components
+-   Libraries that involve user interfaces, e.g. any reference to `View`
+    classes, must provide non-`View` interoperability with the Compose UI
+    toolkit
 
 ### 9. Designed for tooling and testability