Fix confusing interaction between @code macro and transpose operator (') in documentation (Bug #34661). * octave.texi: Define new @xcode macro which expands to nothing in plain text or Info output. Expands to normal @code for all other formats. * data.cc: Rephrase documentation for functions which have operator equivalents. Use @xcode macro to mark the operator equivalent for these functions. * expr.txi: Use @asis markup in table to prevent confusion between transpose operator and @code expansion in Info format. * mk_doc_cache.m, __makeinfo__.m: Add processing for new @xcode macro. * krylov.m, etreeplot.m, lu.cc, schur.cc, symbfact.cc: Use new @xcode macro.