[linalg.algs.blas1.matonenorm] Use \tcode for A (cplusplus#8948)

Author: hewillk

source/numerics.tex

@@ -14128,7 +14128,7 @@
 \item
 \tcode{init} if \tcode{A.extent(1)} is zero;
 \item
-otherwise, the sum of \tcode{init} and the one norm of the matrix $A$.
+otherwise, the sum of \tcode{init} and the one norm of the matrix \tcode{A}.
 \end{itemize}
 \begin{note}
 The one norm of the matrix \tcode{A}