spack.md missing https

docs/software/spack.md

@@ -131,21 +131,21 @@ $ spack load <tool>
 Develop 
 More to come... Meanwhile: 
 
-[Developer guide](spack.readthedocs.io/en/latest/developer_guide.html)
+[Developer guide](https://spack.readthedocs.io/en/latest/developer_guide.html)
 
-[Developer workflows tutorial](spack-tutorial.readthedocs.io/en/lanl19/tutorial_developer_workflows.html)
+[Developer workflows tutorial](https://spack-tutorial.readthedocs.io/en/lanl19/tutorial_developer_workflows.html)
 
 The builds are by default located here: 
 
 $ spack-root//opt/spack/linux-centos7-broadwell/<compiler-version>/
 Packages and environments
 More to come... Meanwhile: 
 
-[Packaging guide](spack-tutorial.readthedocs.io/en/lanl19/tutorial_developer_workflows.html)
+[Packaging guide](https://spack-tutorial.readthedocs.io/en/lanl19/tutorial_developer_workflows.html)
 
-[Environments guide](spack.readthedocs.io/en/latest/environments.html)
+[Environments guide](https://spack.readthedocs.io/en/latest/environments.html)
 
-[Environments tutorial](spack-tutorial.readthedocs.io/en/lanl19/tutorial_environments.html)
+[Environments tutorial](https://spack-tutorial.readthedocs.io/en/lanl19/tutorial_environments.html)
 
 ## Garbage collection
 Installing and uninstalling softwares will in the end use up your disk space so it is good practice to do some garbage collection