minor updates (sec 13)

Chapter13/Figures/figure-reinforcement-learning-method-based-on-actor-critic.tex

@@ -5,7 +5,7 @@
 
 	\node[anchor=west,inner sep=0mm,minimum height=4em,minimum width=5.5em,rounded corners=15pt,align=left,draw,fill=green!20] (n2) at ([xshift=10em,yshift=0em]n1.east) {Decoder\\Encoder};
 
-	\node[anchor=south,inner sep=0mm,font=\small] (a1) at ([xshift=0em,yshift=1em]n1.north) {演员$p_{\theta}$};
+	\node[anchor=south,inner sep=0mm,font=\small] (a1) at ([xshift=0em,yshift=1em]n1.north) {演员$p$};
 
 	\node[anchor=north,inner sep=0mm] (a2) at ([xshift=0em,yshift=-1em]n1.south) {$x$};