* [Doc] Update Data Preparation and Visualization doc

* upload visualization figure example

* fix

* fix

* delete demo image

* remove segvisualizer

* fix

* fix

* fix

* [Fix] README for mmseg 1.x

* typo

* link and refine

* [WIP] Refine documentation

* get started done

* config refine

* train_test

* refine user guides

* add contribution

* add contribution

* refine visualization

* advanced tutorial

* advanced guides

* tricks

* refine zh doc

* refactor changelog

* inference, train_test tutorial

* fix

* add --work-dir

* config tutorial

* update config name convention

* minor change

* rewrite name

* modify scripts dirname

* update links

* [Doc] MMSeg 1.x Documentation

* revise index