03-homework1.md: Add documentation links

week1/03-homework1.md

@@ -13,6 +13,8 @@ You can always refer to:
   * [the example guide](https://gitlab.epfl.ch/lamp/cs-210-functional-programming-2019/blob/master/week1/01-example.md) on the development workflow.
   * [this guide](https://gitlab.epfl.ch/lamp/cs-210-functional-programming-2019/blob/master/week1/02-grading-and-submission.md) for details on the submission system.
     **Make sure to submit your assignment before the deadline written in [README.md](/README.md)**
+  * [The documentation of the Scala standard library](https://www.scala-lang.org/files/archive/api/2.13.1)
+  * [The documentation of the Java standard library](https://docs.oracle.com/en/java/javase/11/docs/api/index.html)
 
 # Exercise 1: Pascal's Triangle
 
@@ -72,6 +74,8 @@ exercise:
 - `chars.head: Char` returns the first element of the list
 - `chars.tail: List[Char]` returns the list without the first element
 
+You can find more information on these methods in the [documentation of List](https://www.scala-lang.org/files/archive/api/2.13.1/scala/collection/immutable/List.html)
+
 __Hint__: you can define an inner function if you need to pass extra
 parameters to your function.