Update start_aws.md (#428)
Update start_aws.md (#428)

changed conda install -c pytorch -c fastai fastai pytorch torchvision cuda92
to conda install -c pytorch -c fastai fastai as the previous one  will break the environment 
Deep Learning AMI (Ubuntu) Version 16.0 is no longer recommend by AWS, so the doc should be updated to Version 24.1
fastai/course-v3,fastai/course-v3,fastai/course-v3,fastai/course-v3,fastai/course-v3,fastai/course-v3,fastai/course-v3