[linalg.algs.blas3.rank2k] Add missing \pnum and \effects (#8801)

Author: abhinavagarwal07

source/numerics.tex

@@ -16038,6 +16038,8 @@
 \end{itemdecl}
 
 \begin{itemdescr}
+\pnum
+\effects
 Computes $C = E + A B^T + B A^T$.
 \end{itemdescr}