[Documentation:Developer] add vagrant-timezone plugin

_docs/developer/getting_started/vm_install_using_vagrant.md

@@ -135,6 +135,7 @@ If you using an Intel-based Mac, you will follow the instructions below._
       ```
       brew install --cask virtualbox
       brew install --cask vagrant
+      vagrant plugin install vagrant-timezone
       ```
 
    * **Windows**  

_docs/developer/getting_started/vm_install_using_vagrant_apple_silicon.md

@@ -59,6 +59,8 @@ the installation process.
 
    $ brew install --cask vagrant
 
+   $ vagrant plugin install vagrant-timezone
+
    $ vagrant plugin install vagrant-qemu
    ```
    Note: It is possible that you may need to install Rosetta before installing vagrant. Run the following command to install Rosetta:

_docs/developer/troubleshooting/installation_troubleshooting.md

@@ -56,6 +56,7 @@ with no explanation, then there are a couple of things that may be going wrong:
     brew reinstall --cask vagrant
     vagrant plugin update
     vagrant box update
+    vagrant plugin install vagrant-timezone
     ```
 
     If you continue to have errors on Mac with `vagrant up` after
@@ -98,11 +99,25 @@ with no explanation, then there are a couple of things that may be going wrong:
   directories/repositories to clean up unwanted VMs.
 
   The following command can help locate misplaced repositories/VMs:
-
   ```
   vagrant global-status
   ```
 
+  If you see unnecessary VMs, you can clean them up with (replace
+  `1a2b3c4d` with the id of the VM you wish to destroy):
+  ```
+  vagrant destroy 1a2b3c4d
+  ```
+
+  If the command above does not successfully destroy and remove the VM from the
+  global-status list, you may see an error similar to: `The machine
+  with the name 'ubuntu-20.04' was not found configured for this
+  Vagrant environment.`  You can try to clean up these undestroyed VMs record by
+  running:
+  ```
+  vagrant global-status --prune
+  ```
+
 * If you might have old, forgotten VMs from previous OS versions
   hanging around it can be helpful to completely delete the `.vagrant`
   folder in your repository.  Also check to see if you have multiple
@@ -169,3 +184,35 @@ broadcast 192.168.56.255
 ```
 
 References and useful links: [https://gist.github.com/pjdietz/5768124](https://gist.github.com/pjdietz/5768124) and [http://christophermaier.name/2010/09/01/host-only-networking-with-virtualbox/](http://christophermaier.name/2010/09/01/host-only-networking-with-virtualbox/)
+
+
+## Guest Additions
+
+
+Submitty vagrant no longer uses Virtual Box Guest Additions.  If you
+see errors about version mismatch with Guest Additions, and if the VM
+hangs trying to update the version of Guest Additions to match the
+host version of Guest Additions, you may have old versions of the
+development process on your machine and may need to more completely
+uninstall and reinstall Virtual Box and Vagrant to reset your system.
+
+**NOTE: THESE ACTIONS WILL DELETE ALL VMS ON YOUR SYSTEM.**
+
+Some things to check:
+
+* From your main Submitty repository, e.g. `<SOMETHING>/GIT_CHECKOUT/Submitty/`
+  run `rm -rf .vagrant`
+
+  (you may need to put sudo in front)
+
+* Check all files on your filesystem for vagrant.  Run 'locate
+  vagrant' and remove any old library / installation files you see.
+  E.g.:
+
+  ```
+  rm /Applications/VirtualBox.app/Contents/MacOS/VBoxGuestAdditions.iso
+  rm -rf /opt/vagrant/
+  rm -rf /Users/MY_HOME_DIRECTORY/.vagrant.d/
+  rm -rf /Users/MY_HOME_DIRECTORY/.gem/specs/rubygems.org%443/quick/Marshal.4.8/vagrant-vbguest-0.31.0.gemspec
+  ```
+