Gluon-nlp: [website] SageMaker/Colab companion for tutorials

[eric-haibin-lin]

d2l.ai currently supports viewing notebooks in colab (see http://d2l.ai/chapter_multilayer-perceptrons/mlp.html as an example). It also contains instructions to run notebooks on Sagemaker http://d2l.ai/chapter_appendix-tools-for-deep-learning/sagemaker.html and colab http://d2l.ai/chapter_appendix-tools-for-deep-learning/aws.html

this makes running tutorial much easier and it would be a good thing to add to gluonnlp website. The only thing is that we need to configure the colab/sagemaker environment the same as the one used on CI to build our website.

[eric-haibin-lin]

@StrayBird-ATSH this one is really useful. Let's include it in the scope