correct typo in programming playgrounds (#6323)

more/free-programming-playgrounds.md

@@ -211,7 +211,7 @@
 * [Codepad](http://codepad.org/?lang=Python)
 * [Python Trinket](https://trinket.io/python)
 * [Python.org Shell](https://www.python.org/shell)
-* [Repl.it - NiceDualPoin](https://repl.it/repls/NiceDualPoint#main.py)
+* [Repl.it - NiceDualPoint](https://repl.it/repls/NiceDualPoint#main.py)
 * [SoloLearn](https://code.sololearn.com/python)