已知数列\(\{a_{n}\}\)是公差不为\(0\)的等差数列，\(a_{1}=2\)，且\(a_{2}\)，\(a_{3}\)，\(a_{4}+1\)成等比数列．
\((\)Ⅰ\()\)求数列\(\{a_{n}\}\)的通项公式；
\((\)Ⅱ\()\)设\(b_{n}= \dfrac {2}{n\cdot (a_{n}+2)}\)，求数列\(\{b_{n}\}\)的前\(n\)项和\(S_{n}\)．