Prune commentary and stale Rust port notes

tabs-ui/Cargo.toml

@@ -3,11 +3,7 @@ name = "tabs-ui"
 version.workspace = true
 edition.workspace = true
 
-# The tabs example's widget tree, factored out of iris/examples/tabs/main.rs
-# so it can be built once and driven by either backend: the winit example
-# binary, and iris/android-app's cdylib. Its own crate rather than a pub
-# module of `iris` because it is demo content, not library surface -- see
-# RUST.md's I2.
+# Shared demo content for the desktop and Android example entry points.
 
 [dependencies]
 iris = { path = ".." }