Slightly change wording in the message

Both `TLoopBoundIsMutatedVariableAccess` and `TLoopStepIsMutatedVariableAccess`
transitively rely on `valueToUpdate`, which overapproximates by looking at the
types alone. Therefore we'd like to drop the confidence slightly in reporting
the expression where the expression *might* have been changed.

Author: jeongsoolee09

cpp/misra/src/rules/RULE-9-5-1/LegacyForStatementsShouldBeSimple.ql

@@ -384,13 +384,13 @@ class AlertType extends TAlertType {
     result = "The $@ is a $@."
     or
     this = TLoopBoundIsMutatedVariableAccess(_, _, _) and
-    result = "The $@ is a non-const expression, or a variable that is $@ in the loop."
+    result = "The $@ is a non-const expression, or a variable that may be $@ in the loop."
     or
     this = TLoopStepIsNonConstExpr(_, _) and
     result = "The $@ is a $@."
     or
     this = TLoopStepIsMutatedVariableAccess(_, _, _) and
-    result = "The $@ is a non-const expression, or a variable that is $@ in the loop."
+    result = "The $@ is a non-const expression, or a variable that may be $@ in the loop."
     or
     this = TLoopCounterIsTakenNonConstAddress(_, _) and
     result = "The $@ is taken as a mutable reference or its address to a mutable pointer."