GitLab

* minor spelling tweaks

* Update CONTRIBUTORS.md

* improve capsule tutorial with jinyang

* fix wrong layout of second-level tutorial

* delete transformer

* model tutorials overview

* update the 1_first

* revised overview and summarized "what is DGL" in glance

* WIP

* new at glance

* update dgl at a glance

* update title

* Update 1_first.py

* minor fix

* jake's change

* refactor API doc; add markup link in tutorials

* fix readme

[Doc] Basic tutorials & two model tutorials

* setup sphinx-gallery; work on graph tutorial

* draft dglgraph tutorial

* update readme to include document url

* rm obsolete file

* Draft the message passing tutorial