Add info how to setup sparse checkout

ReadMe.md

@@ -95,3 +95,13 @@ OR
     }
 }
 ```
+
+## www folder init on udon
+
+```sh
+git init
+git sparse-checkout init
+git sparse-checkout set www
+git remote set-url egra-gitea https://git.egplusww.jp/Composer/Composer-Index.git
+git pull egra-gitea master
+```