Fix an extra newline in rendered std doc

Fixes rust-lang#132564

Author: uellenberg

library/std/src/lib.rs

@@ -32,11 +32,9 @@
 //!
 //! Once you are familiar with the contents of the standard library you may
 //! begin to find the verbosity of the prose distracting. At this stage in your
-//! development you may want to press the <code>
-//! <svg style="width:0.75rem;height:0.75rem" viewBox="0 0 12 12"
-//! stroke="currentColor" fill="none">
-//! <path d="M2,2l4,4l4,-4M2,6l4,4l4,-4"/></svg> Summary</code> button near the
-//! top of the page to collapse it into a more skimmable view.
+//! development you may want to press the
+//! <code><svg style="width:0.75rem;height:0.75rem" viewBox="0 0 12 12" stroke="currentColor" fill="none"><path d="M2,2l4,4l4,-4M2,6l4,4l4,-4"/></svg> Summary</code>
+//! button near the top of the page to collapse it into a more skimmable view.
 //!
 //! While you are looking at the top of the page, also notice the
 //! <code>source</code> link. Rust's API documentation comes with the source