Fix typo in derived

Thanks to  Elías Guisado
https://stacks.math.columbia.edu/tag/015D#comment-8401

derived.tex

@@ -5635,7 +5635,7 @@ \section{Higher derived functors}
 By
 Lemma \ref{lemma-derived-canonical-delta-functor}
 we obtain a distinguished triangle
-$(A[0], B[0], C[0], a, b, c)$ in $K^{+}(\mathcal{A})$.
+$(A[0], B[0], C[0], a, b, c)$ in $D^{+}(\mathcal{A})$.
 As $RF$ is an exact functor and since
 $R^iF = 0$ for $i < 0$ and $R^0F = F$
 (Lemma \ref{lemma-left-exact-higher-derived})