[cpp.embed.gen] Fix italics around "implementation-resource-width" (#7755)

Author: xmcgcg

source/preprocessor.tex

@@ -882,13 +882,13 @@
 
 \pnum
 A resource is a source of data accessible from the translation environment.
-A resource has an \gterm{implementation-resource-width}, which is the
+A resource has an \defn{implementation-resource-width}, which is the
 \impldef{size in bits of a resource}
 size in bits of the resource.
-If the \gterm{implementation-resource-width} is not an integral multiple of
+If the implementation-resource-width is not an integral multiple of
 \libmacro{CHAR_BIT}, the program is ill-formed.
 Let \defn{implementation-resource-count} be
-\gterm{implementation-resource-width} divided by \libmacro{CHAR_BIT}.
+implementation-resource-width divided by \libmacro{CHAR_BIT}.
 Every resource also has a \defn{resource-count}, which is
 
 \begin{itemize}