Reword abi.link_section.unsafe to match attribute template

Author: ehuss

src/abi.md

@@ -122,7 +122,7 @@ Only the last instance of `link_section` on an item is honored. Previous `link_s
 > `rustc` currently warns on preceding duplicate `link_section` attributes. This may become an error in the future.
 
 r[abi.link_section.unsafe]
-This attribute is unsafe as it allows users to place data and code into sections of memory not expecting them, such as mutable data into read-only areas.
+The `link_section` attribute must be marked with [`unsafe`][attributes.safety] because it allows users to place data and code into sections of memory not expecting them, such as mutable data into read-only areas.
 
 r[abi.link_section.edition2024]
 > [!EDITION-2024]