Merge pull request #1786 from lonvia/remove-ubuntu-1604

remove Ubuntu 16 installation instructions

diff --combined docs/admin/Installation.md
index 25b4f14ce1d8ea9f288e2dc5d42752822262c568,a02b48e2a2d7fcaea3202ef54f8fe8f1cdecbf9a..1989a9c070e53321bc544eb98145346508ef5d66
--- 1/docs/admin/Installation.md
--- 2/docs/admin/Installation.md
+++ b/docs/admin/Installation.md
@@@ -6,7 -6,7 +6,7 @@@ the following operating systems
  
    * [Ubuntu 20.04](../appendix/Install-on-Ubuntu-20.md)
    * [Ubuntu 18.04](../appendix/Install-on-Ubuntu-18.md)
-   * [Ubuntu 16.04](../appendix/Install-on-Ubuntu-16.md)
+   * [CentOS 8](../appendix/Install-on-Centos-8.md)
    * [CentOS 7.2](../appendix/Install-on-Centos-7.md)
  
  These OS-specific instructions can also be found in executable form
@@@ -57,7 -57,7 +57,7 @@@ For running tests
  
    * [behave](http://pythonhosted.org/behave/)
    * [nose](https://nose.readthedocs.io)
 -  * [phpunit](https://phpunit.de)
 +  * [phpunit](https://phpunit.de) >= 7.3
  
  ### Hardware