docs(rustdoc): repair the two links that broke the gate this branch added

The rustdoc gate is one this branch put in CI, and this branch had left it
failing — which is the worst state for a gate to be in, since it reads as
enforced and enforces nothing.

`displayed_registry` was the lower-case spelling of `DisplayedRegistry`, so
it resolves now. `PIP_SIZE` names nothing anywhere in the tree; rather than
guess which constant it used to be, the sentence now points at the rem-sized
constants it was contrasting against, which is the part that was actually
true.

All six CI gates now pass as CI runs them: fmt, host boundary, clippy with
`-D warnings`, rustdoc with `-D warnings`, the suite under `--locked`, and
the updater's own feature build.

src/terminal/view.rs

@@ -216,7 +216,7 @@ pub struct TerminalView {
     /// "preparation failed" — see [`staging_cache`].
     remote_clipboard_dir: Option<String>,
     pub focus_handle: FocusHandle,
-    /// See [`displayed_registry`]. Shared with the registry so the app can
+    /// See [`DisplayedRegistry`]. Shared with the registry so the app can
     /// flip it during a draw without an entity access.
     displayed: std::sync::Arc<std::sync::atomic::AtomicBool>,
     pub font: Font,

src/ui/right_panel.rs

@@ -1443,8 +1443,8 @@ pub(crate) fn git_badge(letter: &str, color: gpui::Hsla, mono: &gpui::SharedStri
 ///
 /// The padding and radius are in pixels while the text is in rems, so the two
 /// stop being derived from each other once the interface font scale leaves
-/// 100%: the text grows and the padding does not. That is the same trap
-/// [`PIP_SIZE`] below is written in rems to avoid, and this chip has not been
+/// 100%: the text grows and the padding does not. That is the same trap the
+/// rem-sized constants above are written to avoid, and this chip has not been
 /// through it yet.
 pub(crate) fn info_chip(
     text: &str,