difference-of-squares: add hint to @Ignore annotation

exercises/difference-of-squares/src/test/java/DifferenceOfSquaresCalculatorTest.java

@@ -19,7 +19,7 @@ public final class DifferenceOfSquaresCalculatorTest {
         assertEquals(expected, actual);
     }
 
-    @Ignore
+    @Ignore("Remove to run test")
     @Test
     public void testSquareOfSum10() {
         final int expected = 3025;
@@ -27,7 +27,7 @@ public final class DifferenceOfSquaresCalculatorTest {
         assertEquals(expected, actual);
     }
 
-    @Ignore
+    @Ignore("Remove to run test")
     @Test
     public void testSquareOfSum100() {
         final int expected = 25502500;
@@ -35,7 +35,7 @@ public final class DifferenceOfSquaresCalculatorTest {
         assertEquals(expected, actual);
     }
 
-    @Ignore
+    @Ignore("Remove to run test")
     @Test
     public void testSumOfSquares5() {
         final int expected = 55;
@@ -43,7 +43,7 @@ public final class DifferenceOfSquaresCalculatorTest {
         assertEquals(expected, actual);
     }
 
-    @Ignore
+    @Ignore("Remove to run test")
     @Test
     public void testSumOfSquares10() {
         final int expected = 385;
@@ -51,7 +51,7 @@ public final class DifferenceOfSquaresCalculatorTest {
         assertEquals(expected, actual);
     }
 
-    @Ignore
+    @Ignore("Remove to run test")
     @Test
     public void testSumOfSquares100() {
         final int expected = 338350;
@@ -59,7 +59,7 @@ public final class DifferenceOfSquaresCalculatorTest {
         assertEquals(expected, actual);
     }
 
-    @Ignore
+    @Ignore("Remove to run test")
     @Test
     public void testDifferenceOfSquares0() {
         final int expected = 0;
@@ -67,7 +67,7 @@ public final class DifferenceOfSquaresCalculatorTest {
         assertEquals(expected, actual);
     }
 
-    @Ignore
+    @Ignore("Remove to run test")
     @Test
     public void testDifferenceOfSquares5() {
         final int expected = 170;
@@ -75,7 +75,7 @@ public final class DifferenceOfSquaresCalculatorTest {
         assertEquals(expected, actual);
     }
 
-    @Ignore
+    @Ignore("Remove to run test")
     @Test
     public void testDifferenceOfSquares10() {
         final int expected = 2640;
@@ -83,7 +83,7 @@ public final class DifferenceOfSquaresCalculatorTest {
         assertEquals(expected, actual);
     }
 
-    @Ignore
+    @Ignore("Remove to run test")
     @Test
     public void testDifferenceOfSquares100() {
         final int expected = 25164150;