Update README.md

Author: sulthonzh

README.md

@@ -1,4 +1,4 @@
 # nested-set
 Golang, manage nested-set and generate to nested tree, with custom table_name
 
-thanks for [github.com/scukonick/nested_set](a href="https://github.com/scukonick/nested_set")
+thanks for [github.com/scukonick/nested_set](https://github.com/scukonick/nested_set)