cppinternals.texi: Document MI optimization

[Neil Booth]

Joseph S. Myers wrote:-

> @var is for metasyntactic variables, not for programming language
> variables.  See the Texinfo manual.

OK.  I've seen you write this before, but had no idea what that, um,
expression meant.  I was in the process of reading the TexInfo manual;
but had not reached the area you mention.

> Why (here and elsewhere) are you using @display rather than @example for
> code examples?

I envisaged it as inset, which I know @display will do.  I wasn't sure
what @example might do in various circumstances.

Neil.