Fix mistake in algebra.tex

Thanks to Antoine Chambert-Loir
http://stacks.math.columbia.edu/tag/00QO#comment-1096

algebra.tex

@@ -28527,11 +28527,12 @@ \section{Colimits and maps of finite presentation}
 $$
 S \to S_\lambda \to S
 $$
-for some $\lambda$. Hence we see that $S$ is finitely generated
-over $R$ (because $S_\lambda$ is). Thus we may choose the system
-such that all transition maps are surjective. In this case
-a factorization of the identity as above can only exist if
-$S = S_\lambda$.
+for some $\lambda$. This impies that $S$
+is finitely presented over $S_\lambda$ by
+Lemma \ref{lemma-compose-finite-type} part (4)
+applied to $S \to S_\lambda \to S$. Applying part (2) of the same
+lemma to $R \to S_\lambda \to S$ we conclude that $S$ is of finite
+presentation over $R$.
 \end{proof}
 
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