Fix typo in more-algebra

THanks to David Roberts
https://stacks.math.columbia.edu/tag/0FNG#comment-6986

more-algebra.tex

@@ -17416,7 +17416,7 @@ \section{Sign rules}
 $$
 K^\bullet \to L^\bullet \to M^\bullet \to K^\bullet[1]
 $$
-where $M^n \to K^{n + 1}$ is the map $\pi^{n + 1} \circ d^n_M \circ s^n$
+where $M^n \to K^{n + 1}$ is the map $\pi^{n + 1} \circ d^n_L \circ s^n$
 if $s$ and $\pi$ are compatible termwise splittings. In other words,
 without the intervention of signs. See
 Derived Categories, Definitions \ref{derived-definition-distinguished-triangle}