Document silent uninstallation of NVDA in the user guide (#17203)
Closes #16966
Summary of the issue:
While it is possible to silently uninstall NVDA from the command line, this option is not documented anywhere.
Description of user facing changes:
Added notes on command line uninstallation of NVDA to the "Command Line Options" section of the user guide.
Description of development approach:
Read the NSIS documentation to ensure there wasn't any nuance I was missing.
Testing strategy:
Tested silently uninstalling NVDA.
Known issues with pull request:
Users may find it confusing that the installer uses Unix-style options, while the uninstaller uses DOS-style options.
