docs: fix typo

Author: Scrum

README.md

@@ -20,7 +20,7 @@ npm i -D posthtml-include
 const { readFileSync } = require('fs')
 
 const posthtml = require('posthtml')
-const include = require('include')
+const include = require('posthtml-include')
 
 const html = readFileSync('index.html')