Fix example not using props (#1030)

Author: amirhhashemi

src/routes/concepts/context.mdx

@@ -109,10 +109,8 @@ import { createSignal, createContext, useContext } from "solid-js";
 import { CounterContext } from "~/context/counter";
 
 export function CounterProvider(props) {
-	let count = 0;
-
 	return (
-		<CounterContext.Provider value={count}>
+		<CounterContext.Provider value={props.count ?? 0}>
 			{props.children}
 		</CounterContext.Provider>
 	);