Update README.md

Author: Matheus2212

README.md

@@ -4,4 +4,6 @@ Class that controls Friendly URL. It is focused on SEO best practices.
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 ## Overview
-This class __construct method accepts a initial $url to work with. It can also be omitted, but then the script will try to use $_SERVER values to build the URL.
+This class __construct method accepts a initial $url to work with. Please note that the $url informed will be used as the ROOT URL (like the <base> HTML tag).
+
+It can also be omitted, but then the script will try to use $_SERVER values to build the URL.