adding chapter 5 link

Author: HeidiSeibold

README.md

@@ -11,7 +11,7 @@ about R and RStudio.
 2. [Lesson 02 Launching Docker](02-Launching-Docker.html)
 3. [Lesson 03 Install packages](03-install-packages.html) 
 4. [Lesson 04 Commit](04-commit.html)
-5. Lesson 05 Dockerhub
+5. [Lesson 05 Dockerhub](05-Dockerhub.html)
 6. [Lesson 06 Dockerfiles](06-dockerfiles.html)
 
 

index.html

@@ -45,7 +45,7 @@ <h2>
 <li>
 <a href="03-install-packages.html">Lesson 03 Install packages</a> </li>
 <li><a href="04-commit.html">Lesson 04 Commit</a></li>
-<li>Lesson 05 Dockerhub</li>
+<li><a href="05-Dockerhub.html">Lesson 05 Dockerhub</a></li>
 <li><a href="06-dockerfiles.html">Lesson 06 Dockerfiles</a></li>
 </ol>
       </section>