update notations and fix typos

pages/Math4111/Math4111_L25.md

@@ -99,7 +99,7 @@ _The $\epsilon$ bound would not hold if we only had pointwise convergence._
 
 $|f_N(x) - f_N(p)| < 3\epsilon$.
 
-EOP
+QED
 
 > Recall: If $(s_n)$ is a sequence in $\mathbb{R}$, then $(s_n)$ converges to $s$ if and only if it is Cauchy.  
 > i.e. $\forall \epsilon > 0$, $\exists N\in \mathbb{N}$, $\forall n, m\geq N$, $|s_n - s_m| < \epsilon$.
@@ -147,7 +147,7 @@ $$
 \end{aligned}
 $$
 
-EOP
+QED
 
 Example: