Fix links to virtual_machines section

doc.zih.tu-dresden.de/docs/software/containers.md

@@ -89,7 +89,7 @@ Creating a container is done by writing a definition file and passing it to
 singularity build myContainer.sif myDefinition.def
 ```
 
-NOTE: This must be done on a machine (or [VM](cloud.md) with root rights.
+NOTE: This must be done on a machine (or [VM](virtual_machines.md) with root rights.
 
 A definition file contains a bootstrap
 [header](https://sylabs.io/guides/3.2/user-guide/definition_files.html#header)

doc.zih.tu-dresden.de/docs/software/get_started_with_hpcda.md

@@ -331,7 +331,7 @@ you have to use the definition file to create the container
 from our wiki. Bootstrapping **has required root privileges** and
 Virtual Machine (VM) should be used! There are two main options on how
 to work with VM on Taurus: [VM tools](vm_tools.md) - automotive algorithms
-for using virtual machines; [Manual method](cloud.md) - it requires more
+for using virtual machines; [Manual method](virtual_machines.md) - it requires more
 operations but gives you more flexibility and reliability.
 
 - [machine_learning_example.py] **todo** %ATTACHURL%/machine_learning_example.py:

doc.zih.tu-dresden.de/docs/software/tensor_flow_container_on_hpcda.md

@@ -47,7 +47,7 @@ on how to work with VM on Taurus:
 1\. [VM tools](vm_tools.md). Automative algorithms for using virtual
 machines;
 
-2\. [Manual method](cloud.md). It required more operations but gives you
+2\. [Manual method](virtual_machines.md). It required more operations but gives you
 more flexibility and reliability.
 
 Short algorithm to run the virtual machine manually:

doc.zih.tu-dresden.de/docs/software/vm_tools.md

@@ -17,7 +17,7 @@ likely doesn't.
 
 For this we provide a Virtual Machine (VM) on the ml partition which allows users to gain root
 permissions in an isolated environment. The workflow to use this manually is described at
-[another page](cloud.md) but is quite cumbersome.
+[another page](virtual_machines.md) but is quite cumbersome.
 
 To make this easier two programs are provided: `buildSingularityImage` and `startInVM` which do what
 they say. The latter is for more advanced use cases so you should be fine using