Change INSTALL.rst on the installation of Windows checks

[jprusch]

Describe the solution you'd like

Right now the INSTALL.rst states:

Nevertheless, the Icinga agent puts its files in c:\programdata\icinga2. This is why we also recommend to use this directory.

Change

• The Icinga2 binaries and default checks are now installed in C:\Program Files\ICINGA2.
• PluginDir on Windows points to C:\Program Files\ICINGA2\sbin

Fix

While the Linuxfabrik Windows checks can be stored in c:\programdata\icinga2\usr\lib64\nagios\plugins, the documentation is not correct on the main cause to put the checks in this directory.
Sudo is not an issue on the Windows side, so using a directory below C:\Program Files\ICINGA2\sbin like

C:\Program Files\ICINGA2\sbin\linuxfabrik

might be a better approach also from the security point of view. PluginDir can then be used and a full path is not needed.

This can be accomplished with an update to the INSTALL documentation.

Additional context

Various Windows OS with suggested deployment method for Icinga For Windows.

[markuslf]

Interesting, thanks. I did a quick installation using Icinga Agent v14.2 and can confirm the paths. This will lead to some changes and testing on our end.