fix typos

content/CSE510/CSE510_L12.md

@@ -81,7 +81,7 @@ Reducing variance using a baseline
 
 $$
 \begin{aligned}
-\mathbb{E}_{\pi_\theta}\left[\nabla_\theta\log \pi_\theta(s,a)B(s)]&=\sum_{s\in S}d^{\pi_\theta}(s)\sum_{a\in A}\nabla_{\theta}\pi_\theta(s,a)B(s)\\
+\mathbb{E}_{\pi_\theta}\left[\nabla_\theta\log \pi_\theta(s,a)B(s)\right]&=\sum_{s\in S}d^{\pi_\theta}(s)\sum_{a\in A}\nabla_{\theta}\pi_\theta(s,a)B(s)\\
 &=\sum_{s\in S}d^{\pi_\theta}B(s)\nabla_\theta\sum_{a\in A}\pi_\theta(s,a)\\
 &=0
 \end{aligned}