[linalg.helpers] Remove redundancies from subordinate headings

Author: jensmaurer

source/numerics.tex

@@ -11858,7 +11858,7 @@
 otherwise, \tcode{((void)E, T\{\})}.
 \end{itemize}
 
-\rSec3[linalg.helpers.concepts]{Linear algebra argument concepts}
+\rSec3[linalg.helpers.concepts]{Argument concepts}
 
 \pnum
 The exposition-only concepts defined in this section
@@ -11945,7 +11945,7 @@
 parameter of a function in \ref{linalg}
 shall not overlap any other \tcode{mdspan} parameter of the function.
 
-\rSec3[linalg.helpers.mandates]{Exposition-only helpers for algorithm mandates}
+\rSec3[linalg.helpers.mandates]{Mandates}
 
 \begin{note}
 These exposition-only helper functions use
@@ -12003,7 +12003,7 @@
   }
 \end{codeblock}
 
-\rSec3[linalg.helpers.precond]{Exposition-only checks for algorithm preconditions}
+\rSec3[linalg.helpers.precond]{Preconditions}
 
 \begin{note}
 These exposition-only helper functions use