Improve exposition proof of Lemma 0ANV

Thanks to Brian Conrad
http://stacks.math.columbia.edu/tag/0ANV#comment-1974

formal-spaces.tex

@@ -4943,8 +4943,11 @@ \section{Algebras topologically of finite type}
 
 \begin{proof}
 Since $X$ and $Y$ are affine it is clear that conditions (1)
-and (2) are equivalent. In cases (1) and (2) we see that
-$X$ is countably indexed as well by
+and (2) are equivalent. In cases (1) and (2) the morphism $f$
+is representable by algebraic spaces by definition, hence
+affine by Lemma \ref{lemma-affine-representable-by-algebraic-spaces}.
+Thus if (1) or (2) holds we see that
+$X$ is countably indexed by
 Lemma \ref{lemma-property-goes-up-affine-morphism}.
 Write $X = \text{Spf}(A)$ and $Y = \text{Spf}(B)$
 for topological $S$-algebras $A$ and $B$ in $\textit{WAdm}^{count}$, see