update doc about codebase deployment

[lvhan028]

Thanks for your contribution and we appreciate it a lot. The following instructions would make your pull request more healthy and more easily receiving feedbacks. If you do not understand some items, don't worry, just make the pull request and seek help from maintainers.

Motivation

In OpenMMLab 2.0, codebases remove model deployment tools and request mmdeploy to provide a guideline instead.

Modification

• [x] mmcls.md
• [x] mmdet.md
• [x] mmseg.md
• [x] mmedit.md
• [x] mmocr.md
• [x] mmpose.md

Depends on #1052

[ZwwWayne]

Suggest using picture links rather than PNG images to reduce the size of the repo.

[lvhan028]

Suggest using picture links rather than PNG images to reduce the size of the repo.

Those images are used as input images when converting pytorch models