fix typos in fine-tuning.md (#372)
fix typos in fine-tuning.md (#372)

* fix object-detection-dataset

* fix typos in fine-tuning.md

d2l-ai/d2l-zh,mli/gluon-tutorials-zh,mli/gluon-tutorials-zh,d2l-ai/d2l-zh,mli/gluon-tutorials-zh,d2l-ai/d2l-zh,mli/gluon-tutorials-zh