user docs: Fix the capitalization on “Color Schemes” (#1953)

Author: ksyx

doc/user-docs/UsingJsonSettings.md

@@ -75,7 +75,7 @@ The profile GUID is used to reference the default profile in the global settings
 
 The values for background image stretch mode are documented [here](https://docs.microsoft.com/en-us/uwp/api/windows.ui.xaml.media.stretch)
 
-##  color Schemes
+##  Color Schemes
 
 Each scheme defines the color values to be used for various terminal escape sequences.
 Each schema is identified by the name field. Examples include