feat: tweak --help message to use :json not :raw

I think this message originated before the :json type was implemented.

Author: h4l

json.bash

@@ -1646,7 +1646,7 @@ Examples:
   $ source json.bash
   $ out=compilerOptions json removeComments:true
   $ files=(a.ts b.ts)
-  $ json @compilerOptions:raw @files:string[]
+  $ json @compilerOptions:json @files:string[]
   {"compilerOptions":{"removeComments":true},"files":["a.ts","b.ts"]}
 
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