Previously, we use `libsvm` as default when format is not specified. However, the dmlc
data parser is not particularly robust against errors, and the most common type of error
is undefined format.
Along with which, we will recommend users to use other data loader instead. We will
continue the maintenance of the parsers as it's currently used for many internal tests
including federated learning.
* Change doc build to reST exclusively
* Rewrite Intro doc in reST; create toctree
* Update parameter and contribute
* Convert tutorials to reST
* Convert Python tutorials to reST
* Convert CLI and Julia docs to reST
* Enable markdown for R vignettes
* Done migrating to reST
* Add guzzle_sphinx_theme to requirements
* Add breathe to requirements
* Fix search bar
* Add link to user forum
