* develop segmentor and remove custom optim

* update segmentor example

* add data preprocessor

* refine intro

* [Docs] Add Overview

* comments

* refine

* refine

* [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

* transform tutorial

* fix

* [Doc] MMSeg 1.x Documentation

* revise index