Change phrase "Run install.bat as administrator" to just "Run install.bat"

[ytsarko]

@winneon, on Windows when you write something into HKCU part of registry you don't need to have administration privileges for that. Please correct instruction for Windows installation by removing wording "as administrator" in item 3. The following command line works just fine on my Windows 10 setup:

REG ADD "HKCU\Software\Google\Chrome\NativeMessagingHosts\moe.winneon.watchwithmpv" /ve /t REG_SZ /d "%~dp0moe.winneon.watchwithmpv.json" /f The operation completed successfully.

It is not secure to run commands with administrator privileges when this actually is not required.