Rollup merge of rust-lang#85141 - GuillaumeGomez:maybe_collapsed_doc_value-doc, r=jsha

Update documentation for SharedContext::maybe_collapsed_doc_value

Fixes rust-lang#85120.

The `doc-collapse` was removed, however, the main crate is always "collapsed", meaning that this function is still needed. I updated the documentation instead to avoid misleading readers.

r? `@jsha`

Author: GuillaumeGomez

src/librustdoc/html/render/context.rs

@@ -137,8 +137,8 @@ impl SharedContext<'_> {
         Ok(())
     }
 
-    /// Based on whether the `collapse-docs` pass was run, return either the `doc_value` or the
-    /// `collapsed_doc_value` of the given item.
+    /// Returns the `collapsed_doc_value` of the given item if this is the main crate, otherwise
+    /// returns the `doc_value`.
     crate fn maybe_collapsed_doc_value<'a>(&self, item: &'a clean::Item) -> Option<String> {
         if self.collapsed { item.collapsed_doc_value() } else { item.doc_value() }
     }