Fix typo in dualizing.tex

Thanks to Sandor Kovacs
http://stacks.math.columbia.edu/tag/0A7P#comment-1692

dualizing.tex

@@ -3364,7 +3364,7 @@ \section{Dualizing complexes over local rings}
 Then we obtain a system of isomorphisms
 $A/\mathfrak m^n \to F(A/\mathfrak m^n)$ compatible with all
 $A$-module maps $A/\mathfrak m^n \to A/\mathfrak m^{n'}$ (by $A$-linearity
-of $F$ again). Since any finite lenghth module is a cokernel
+of $F$ again). Since any finite length module is a cokernel
 of a map between direct sums of cyclic modules, we obtain the isomorphism
 of the lemma.
 \end{proof}