fix 11.10

docs/chapter11/chapter11.md

@@ -76,7 +76,7 @@ $$
 &=\frac{L}{2}\left\|\boldsymbol{x}-\left(\boldsymbol{x}_{k}-\frac{1}{L} \nabla f\left(\boldsymbol{x}_{k}\right)\right)\right\|_{2}^{2}+\mathrm{const}
 \end{aligned}
 $$
-其中$\mathrm{const}=f(x_k)--\frac{1}{2 L} \nabla f\left(x_{k}\right)^{\top} \nabla f\left(x_{k}\right)$
+其中$\mathrm{const}=f(x_k)-\frac{1}{2 L} \nabla f\left(x_{k}\right)^{\top} \nabla f\left(x_{k}\right)$