Document / lockdown more of GPUI

crates/gpui/src/shared_string.rs

@@ -3,6 +3,8 @@ use serde::{Deserialize, Serialize};
 use std::{borrow::Borrow, sync::Arc};
 use util::arc_cow::ArcCow;
 
+/// A shared string is an immutable string that can be cheaply cloned in GPUI
+/// tasks. Essentially an abstraction over an Arc<str> and &'static str,
 #[derive(Deref, DerefMut, Eq, PartialEq, Hash, Clone)]
 pub struct SharedString(ArcCow<'static, str>);