Fix erroneous example

Thanks to Laurent Moret-Bailly
https://stacks.math.columbia.edu/tag/04N3#comment-6999

spaces-properties.tex

@@ -1210,9 +1210,9 @@ \section{Dimension at a point}
 Warning: It is {\bf not} the case that $\dim_x(X) = \dim_x(|X|)$
 in general. A counter example is the algebraic space $X$ of
 Spaces, Example \ref{spaces-example-infinite-product}.
-Namely, in this example we have $\dim_x(X) = 0$ and
-$\dim_x(|X|) = 1$ (this holds for any $x \in |X|$).
-In particular, it also means that the dimension of $X$ (as defined
+Namely, let $x \in |X|$ be a point not equal to the generic point $x_0$
+of $|X|$. Then we have $\dim_x(X) = 0$ but $\dim_x(|X|) = 1$.
+In particular, the dimension of $X$ (as defined
 below) is different from the dimension of $|X|$.
 
 \begin{definition}