[Docs] yolov5_description.md in English (open-mmlab#198)

* draft 1 yolov5_descrip_eng

* Update docs/en/algorithm_descriptions/yolov5_description.md

Co-authored-by: HinGwenWoong <[email protected]>

* Update docs/en/algorithm_descriptions/yolov5_description.md

Co-authored-by: HinGwenWoong <[email protected]>

* Update docs/en/algorithm_descriptions/yolov5_description.md

Co-authored-by: HinGwenWoong <[email protected]>

* add section 1.3

* draft finished

* update docs

* Update docs/en/algorithm_descriptions/yolov5_description.md

Co-authored-by: HinGwenWoong <[email protected]>

* remove unnecessary parts

* Update docs/zh_cn/algorithm_descriptions/yolov5_description.md

Co-authored-by: Range King <[email protected]>

* Update docs/en/algorithm_descriptions/yolov5_description.md

Co-authored-by: Range King <[email protected]>

* Update docs/en/algorithm_descriptions/yolov5_description.md

Co-authored-by: Range King <[email protected]>

* Update docs/en/algorithm_descriptions/yolov5_description.md

Co-authored-by: Range King <[email protected]>

* Update docs/en/algorithm_descriptions/yolov5_description.md

Co-authored-by: Range King <[email protected]>

* Update docs/en/algorithm_descriptions/yolov5_description.md

Co-authored-by: Range King <[email protected]>

* Update docs/en/algorithm_descriptions/yolov5_description.md

Co-authored-by: Range King <[email protected]>

* Update docs/en/algorithm_descriptions/yolov5_description.md

Co-authored-by: Range King <[email protected]>

* open-sourced -> open-source

* merge&update

* assignment strategy&merge dev branch

Co-authored-by: HinGwenWoong <[email protected]>
Co-authored-by: Range King <[email protected]>