Document command line uninstallation of NVDA in the user guide

[coderabbitai]

Per @wmhn1872265132's Comment, NVDA can be uninstalled silently through uninstall.exe /S. However, this process is not documented.

The following actions are suggested:

1. Document the silent uninstall switch in https://www.nvaccess.org/files/nvda/documentation/userGuide.html#CommandLineOptions.
2. Consider adding an uninstall option (and associated command-line switch) to force deletion of add-ons and configuration files.

This documentation would greatly assist IT services in deploying NVDA more efficiently.

Referenced Issues:

• Add-ons use disk space after NVDA is uninstalled #6869: Add-ons left after uninstall.
• Add option to installation routine to choose whether to keep previous configuration (where one is found) #9596: Option to prompt whether to use or remove old configurations on install.

For further context, see the discussion in Issue #16892.

[mbexonexp]

Does this actually work, I have just been trying it and it still shows the uninstall dialog.

[SaschaCowley]

@mbexonexp I just tried in a Sandbox and it worked fine for me. Note that the /S must be a capital 'S'.