We can quickly access the documentation of any Unity keyword or class by highlighting it in Visual Studio Community and pressing Ctrl + ' (cmd + '). This will open the default browser and perform a search on the Unity documentation for the given keyword or class.
Note that users with European keyboards may also need to hold down the Shift key for this feature to work.
The same can be done in Visual Studio by pressing Ctrl + Alt + M, followed by Ctrl + H.