Update source/lib-intro.tex

Co-authored-by: Johel Ernesto Guerrero Peña <[email protected]>

Author: jensmaurer

source/lib-intro.tex

@@ -949,10 +949,9 @@
 \end{example}
 
 \pnum
-\indextext{function!freestanding deleted}%
 Function declarations and function template declarations
 followed by a comment that include \textit{freestanding-deleted} are
-freestanding deleted functions.
+\defnadjx{freestanding deleted}{functions}{function}.
 On freestanding implementations,
 it is \impldef{whether a freestanding deleted function is a freestanding item or a deleted function}
 whether each function definition introduced by a freestanding deleted function