For what values k is the following function continuous at x=-\dfrac{\pi}{6} ?
f\left( x \right) = \left\{ \begin{array}{l}\dfrac{{\sqrt 3 \sin x + \cos x}}{{x + \dfrac{\pi }{6}}}\,,\,x \ne - \dfrac{\pi }{6}\\\,\,\,\,\,\,\,\,\,\,\,\,\,\,k\,\,\,\,\,\,\,\,\,\,\,\,\,\,,x = - \dfrac{\pi }{6}\end{array} \right.