fix error message during create-next-app (#26980)

Fixes [issue #19588](#19588)

Here's a screenshot of the error message:
![image](https://user-images.githubusercontent.com/30517208/124733436-d1babd80-df31-11eb-96e4-513505ba07a0.png)

Author: anindya-dey

packages/create-next-app/create-app.ts

@@ -89,7 +89,11 @@ export async function createApp({
         console.error(
           `Could not locate an example named ${chalk.red(
             `"${example}"`
-          )}. Please check your spelling and try again.`
+          )}. It could be due to the following:\n`,
+          `1. Your spelling of example ${chalk.red(
+            `"${example}"`
+          )} might be incorrect.\n`,
+          `2. You might not be connected to the internet.`
         )
         process.exit(1)
       }