Update README.md

asked copilot to be sure, here is the answer:

The phrase “look below code” is not grammatically correct. The correct version should be “Look at the code below.” The preposition “at” is necessary to indicate the direction of looking.

README.md

@@ -38,7 +38,7 @@ We use this formula to calculate the difference : (B - A) ÷ A \* 100
 
 # A little trip
 
-### Look below code:
+### Look at the code below:
 
 Create a file called `mod.ts` and paste the code below into it: