Update: Readme with leaveCssFile

Author: tristyb

Diff for: README.md

@@ -57,6 +57,7 @@ interface Config {
     target: string
     position?: 'before' | 'after'
     removeTarget?: boolean
+    leaveCssFile?: boolean
   }
 }
 ```
@@ -83,6 +84,7 @@ replace?: {
   target: string
   position?: 'before' | 'after' // default is 'before'
   removeTarget?: boolean // default is false
+  leaveCssFile?: boolean // default is false
 }
 ```
 A config for customizing the location of injection, default will add internal style sheet before the `</head>`
@@ -92,6 +94,8 @@ A target for adding the internal style sheet
 Add internal style sheet `before`/`after` the `target`
 #### removeTarget(optional)
 if `true`, it will remove the `target` from the output HTML
+#### leaveCssFile(optional)
+if `true`, it will leave CSS files where they are when inlining
 
 ##### example
 ```html