Auxin is the plant growth hormone that is synthesized at the shoot tip.
Yes, it is true that shoot of a plant bends towards the light during its growth and it is due to the presence of this auxin growth hormone. In the presence of sunlight, the auxin present in the stem starts breaking down due to which the concentration of auxin in the stem which is away from sunlight is more while those part of stem which is towards sunlight has low level of auxin. The cells with high level of auxin grow and the part having low level of auxin does not grow and therefore, stem of growing plant bend toward sunlight.
Following picture depicts the phenomenon: