bsn: improve docs and add tests

Cargo.toml

@@ -5208,6 +5208,9 @@ rustdoc-args = [
   "docs-rs/trait-tags.html",
 ]
 all-features = true
+# approximately equal comand for docs.rs like build locally
+# excluding example scraping and adding mergable info for compile speed
+# cargo doc --lib -Zrustdoc-mergeable-info --config 'build.rustflags=["--cfg", "docsrs_dep"]' -Zhost-config -Ztarget-applies-to-host --config 'host.rustflags=["--cfg", "docsrs_dep"]' --config 'build.rustdocflags=["-Zunstable-options", "--generate-link-to-definition", "--generate-macro-expansion", "--html-after-content", "./docs-rs/trait-tags.html"]' --no-deps -p bevy --all-features
 
 [[example]]
 name = "monitor_info"

crates/bevy_ecs/src/template.rs

@@ -416,6 +416,8 @@ impl<T: Clone + Default + Unpin> FromTemplate for T {
 pub trait SpecializeFromTemplate: Sized {}
 
 /// A [`Template`] reference to an [`Entity`].
+///
+/// This is only valid during scene spawning and should **never** be used as a [`Component`](bevy_ecs::prelude::Component) field.
 #[derive(Copy, Clone, Default, Debug)]
 pub enum EntityTemplate {
     /// A reference to a specific [`Entity`]