chore: put citations in table

Author: manhatsu

src/coding-guidelines/types-and-traits.rst

@@ -285,10 +285,14 @@ Types and Traits
       :id: bib_UnionFieldValidity
       :status: draft
 
-      .. [RUST-REF-UNION] The Rust Project Developers. “Rust Reference: Unions.” *The Rust Reference*, n.d. https://doc.rust-lang.org/reference/items/unions.html.
-      .. [UCG-VALIDITY] Rust Unsafe Code Guidelines Working Group. “Validity and Safety Invariant.” *Rust Unsafe Code Guidelines*, n.d. https://rust-lang.github.io/unsafe-code-guidelines/glossary.html#validity-and-safety-invariant.
-
-
+      .. list-table::
+         :header-rows: 0
+         :widths: 10 80
+
+         * - .. [RUST-REF-UNION]
+           - The Rust Project Developers. "Rust Reference: Unions." *The Rust Reference*, n.d. https://doc.rust-lang.org/reference/items/unions.html.
+         * - .. [UCG-VALIDITY]
+           - Rust Unsafe Code Guidelines Working Group. "Validity and Safety Invariant." *Rust Unsafe Code Guidelines*, n.d. https://rust-lang.github.io/unsafe-code-guidelines/glossary.html#validity-and-safety-invariant.
 
 .. guideline:: Use strong types to differentiate between logically distinct values
    :id: gui_xztNdXA2oFNC