Fix comment to KT-3370 about no formatting of spaces around colon in objects

#KT-3370 Fixed

idea/testData/formatter/SpaceAroundExtendColonInObjects.kt

@@ -0,0 +1,34 @@
+trait A
+
+object Some1     :    A {
+
+}
+
+object Some2:A
+
+object Some3
+
+:
+
+
+A
+
+val a = object:A {}
+
+val b = object   :      A {}
+
+class B {
+    class object:A {
+
+    }
+}
+
+class C {
+    class object   :
+    A {
+
+    }
+}
+
+// SET_TRUE: SPACE_BEFORE_EXTEND_COLON
+// SET_FALSE: SPACE_AFTER_EXTEND_COLON