Insert future reference

Thanks to Gabriel Ribeiro
https://stacks.math.columbia.edu/tag/09IB#comment-7466

fields.tex

@@ -3544,7 +3544,8 @@ \section{Transcendence}
 ``field of rational functions'': basically, functions that look like
 quotients of polynomials, where the denominator does not identically
 vanish on the curve. There is a similar anti-equivalence of categories
-(insert future reference here) between smooth projective curves and
+(Curves, Theorem \ref{curves-theorem-curves-rational-maps})
+between smooth projective curves and
 non-constant morphisms of curves and finitely generated extensions of $k$ of
 transcendence degree one. See \cite{H}.
 \end{example}