Merge pull request #1410 from FridaTveit/PoliciesReferenceTutorial

Add reference tutorial policy

CONTRIBUTING.md

 
 There is a [general Exercism guide for porting an exercise to a new language](https://github.com/exercism/docs/blob/master/you-can-help/implement-an-exercise-from-specification.md).
 Please review this before porting an exercise to the Java track.
- 
+
 See [here](http://exercism.io/languages/java/todo) for a list of exercises that have yet to be implemented on the Java track and can therefore be ported to this track.
 Please make sure no one else has a pull request open to implement your chosen exercise before you start.
 Also please make a [dibs pull request](https://github.com/exercism/docs/blob/master/you-can-help/implement-an-exercise-from-specification.md#avoiding-duplicate-work) to make it clear to others that you are working on this exercise.
 The canonical data version can be found at the top of the canonical data file for that exercise.
 See other exercises, e.g. [acronym](https://github.com/exercism/java/tree/master/exercises/acronym/.meta), for an example `version` file.
 
+* Make sure you've followed the [track policies](https://github.com/exercism/java/blob/master/POLICIES.md), especially the ones for exercise added/updated.
+
 Hopefully that should be enough information to help you port an exercise to the Java track.
 Feel free to open an issue or post in the [Gitter exercism/java room](https://gitter.im/exercism/java) if you have any questions and we'll try and answer as soon as we can.

POLICIES.md

 
 | Track Event | Policies to review |
 |:------------|:-----------------|
-| Exercise added/updated | [Prefer instance methods](#prefer-instance-methods); [Avoid using final](#avoid-using-final); [Adhere to best practices](#adhere-to-best-practices); [Starter implementations](#starter-implementations); [Ignore noninitial tests](#ignore-noninitial-tests); [Multiple file submissions](#multiple-file-submissions); [Name test class after class under test](#name-test-class-after-class-under-test); [Add hint for the first exercises without starter implementation](#add-hint-for-the-first-exercises-without-starter-implementation)
+| Exercise added/updated | [Prefer instance methods](#prefer-instance-methods); [Avoid using final](#avoid-using-final); [Adhere to best practices](#adhere-to-best-practices); [Starter implementations](#starter-implementations); [Ignore noninitial tests](#ignore-noninitial-tests); [Multiple file submissions](#multiple-file-submissions); [Name test class after class under test](#name-test-class-after-class-under-test); [Add hint for the first exercises without starter implementation](#add-hint-for-the-first-exercises-without-starter-implementation); [Reference tutorial in the first exercises](#reference-tutorial-in-the-first-exercises)
 | Track rearranged | [Starter implementations](#starter-implementations); [Multiple file submissions](#multiple-file-submissions) |
 | New issue observed in track | [Good first patches](#good-first-patches) |
 | "Good first patch" issue completed | [Good first patches](#good-first-patches) |
 
 ### Name test class after class under test
 
-> If you're testing a class called `SomeClassName` then your test class should be called `SomeClassNameTest`. 
+> If you're testing a class called `SomeClassName` then your test class should be called `SomeClassNameTest`.
 
 > The exception to this is if the tests are split into several test classes where each test class tests different functionality. In that case each class should be named `SomeClassNameFunctionalityTest` where `Functionality` is the name of the functionality to be tested in that class. See the [clock exercise](https://github.com/exercism/java/tree/master/exercises/clock) as an example.
 
 > We add the file to every exercise with difficulty 5 because the structure of the track means that we don't know which exercise will be the first one without starter implementation that a user will be faced with.
 
 References: [[1](https://github.com/exercism/java/issues/1075)]
+
+### Reference tutorial in the first exercises
+
+> The hello world exercise has an extensive tutorial on how to solve exercism exercises.
+> This tutorial would probably be useful to have as a reference when solving some of the other earlier exercises as well.
+> Therefore any exercise with difficulty less than 3 should have a hints.md file which references [the hello world tutorial](https://github.com/exercism/java/blob/master/exercises/hello-world/TUTORIAL.md).
+
+References: [[1](https://github.com/exercism/java/issues/1389)]