Fix in example code.

Fixed the function name in the example code. This one was left unnoticed in my previous commit. There may be other similar bugs in other pages in the Character section. I am catching them as I translate the reference to Portuguese.

Author: robsoncouto

Language/Functions/Characters/isUpperCase.adoc

@@ -51,7 +51,7 @@ Analyse if a char is upper case (that is a letter in upper case). Returns true i
 
 [source,arduino]
 ----
-if (isAlpha(this))      // tests if this is an upeer case letter
+if (isUpperCase(this))      // tests if this is an upeer case letter
 {
 	Serial.println("The character is upper case");
 }