updated link for two Scala resources (#3372)

✔ Updated link of A Scala tutorial for Java programmers

✔ Updated link of Scala by Example

free-programming-books.md

@@ -2365,7 +2365,7 @@ Kerridge (PDF) (email address *requested*, not required)
 
 ### Scala
 
-* [A Scala Tutorial for Java programmers](http://www.scala-lang.org/docu/files/ScalaTutorial.pdf) (PDF)
+* [A Scala Tutorial for Java programmers](https://docs.scala-lang.org/tutorials/scala-for-java-programmers.html) (PDF)
 * [Advanced Scala with Cats](http://underscore.io/books/advanced-scala/) - Noel Welsh and Dave Gurnell (PDF, HTML, EPUB) (email address *requested*, not required)
 * [Another tour of Scala](http://naildrivin5.com/scalatour/)
 * [Creative Scala](http://underscore.io/books/creative-scala/) - Noel Welsh and Dave Gurnell (PDF, HTML, EPUB) (email address *requested*, not required)
@@ -2382,7 +2382,7 @@ Kerridge (PDF) (email address *requested*, not required)
 * [PythonToScala](https://wrobstory.gitbooks.io/python-to-scala/content/) - Rob Story
 * [S-99: Ninety-Nine Scala Problems](http://aperiodic.net/phil/scala/s-99/) - Phil! Gold
 * [Scala & Design Patterns: Exploring Language Expressivity](http://www.scala-lang.org/old/sites/default/files/FrederikThesis.pdf) - Fredrik Skeel Løkke (PDF)
-* [Scala By Example](http://www.scala-lang.org/docu/files/ScalaByExample.pdf) - M. Odersky (PDF)
+* [Scala By Example](https://www.scala-lang.org/old/sites/default/files/linuxsoft_archives/docu/files/ScalaByExample.pdf) - M. Odersky (PDF)
 * [Scala Cookbook: Bonus Chapters](http://examples.oreilly.com/9781449339616-files/Scala_Cookbook_bonus_chapters.pdf) - Alvin Alexander (PDF)
 * [Scala for Perl 5 Programmers](https://github.com/garu/scala-for-perl5-programmers) - Breno G. de Oliveira
 * [Scala for the Impatient (A1 Scala Level chapters)](http://www.typesafe.com/resources/e-books) - Cay S. Horstmann