[intro.refs] Fix title of ISO/IEC 9899:2018

Fixes ISO/CS 004 (C++23 DIS).

Author: jensmaurer

source/intro.tex

@@ -37,7 +37,7 @@
 \item ISO/IEC 2382, \doccite{Information technology --- Vocabulary}
 \item ISO 8601:2004, \doccite{Data elements and interchange formats ---
 Information interchange --- Representation of dates and times}
-\item ISO/IEC 9899:2018, \doccite{Programming languages --- C}
+\item ISO/IEC 9899:2018, \doccite{Information technology --- Programming languages --- C}
 \item ISO/IEC/IEEE 9945:2009, \doccite{Information Technology --- Portable
 Operating System Interface (POSIX
 \begin{footnote}