[Doc] Add Chinese version of getting start doc

[BIGWangYuDong]

This PR adds a Chinese version of getting_start.

Meanwhile, this PR also called on the community to produce Chinese documents. (Adding News in README.md and READ_zh_CN.md)

[codecov]

Codecov Report

Merging #5421 (c0f1f68) into master (b6f4366) will decrease coverage by 0.21%.
The diff coverage is n/a.

❗ Current head c0f1f68 differs from pull request most recent head 803eba6. Consider uploading reports for the commit 803eba6 to get more accurate results

@@            Coverage Diff             @@
##           master    #5421      +/-   ##
==========================================
- Coverage   65.25%   65.04%   -0.22%     
==========================================
  Files         276      276              
  Lines       21528    21379     -149     
  Branches     3560     3560              
==========================================
- Hits        14048    13905     -143     
+ Misses       6727     6712      -15     
- Partials      753      762       +9     

Flag	Coverage Δ
unittests	65.02% <ø> (-0.20%)	⬇️

Flags with carried forward coverage won't be shown. Click here to find out more.

Impacted Files	Coverage Δ
mmdet/models/dense_heads/anchor_head.py	86.72% <ø> (ø)
mmdet/models/detectors/base.py	51.21% <0.00%> (-2.63%)	⬇️
mmdet/models/dense_heads/dense_test_mixins.py	41.02% <0.00%> (-2.57%)	⬇️
mmdet/models/roi_heads/test_mixins.py	54.83% <0.00%> (-2.42%)	⬇️
mmdet/models/roi_heads/base_roi_head.py	85.29% <0.00%> (-2.21%)	⬇️
mmdet/datasets/pipelines/formating.py	64.22% <0.00%> (-2.16%)	⬇️
mmdet/core/bbox/coder/yolo_bbox_coder.py	58.97% <0.00%> (-2.01%)	⬇️
mmdet/core/anchor/point_generator.py	51.57% <0.00%> (-1.96%)	⬇️
mmdet/core/export/onnx_helper.py	30.76% <0.00%> (-1.49%)	⬇️
mmdet/datasets/pipelines/instaboost.py	13.55% <0.00%> (-1.45%)	⬇️
... and 49 more

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[ZwwWayne]

Need to resolve conflicts.