[simd.unary] Add \ref for simd.unary (#7908)

Author: Andreas-Krug

source/numerics.tex

@@ -17540,7 +17540,7 @@
 \rSec3[simd.unary]{\tcode{basic_simd} unary operators}
 
 \pnum
-Effects in [simd.unary] are applied as unary element-wise operations.
+Effects in \ref{simd.unary} are applied as unary element-wise operations.
 
 \begin{itemdecl}
 constexpr basic_simd& operator++() noexcept;