Updates Huawei Device Type: S6720-30C-EI-24S-AC (#3347)

* Adds 'huawei-s6720-30c-ei-24s-ac.front.png'

* Adds 'huawei-s6720-30c-ei-24s-ac.rear.png'

* Modifies S6720-30C-EI-24S-AC.yaml -> adds elevation images

* Adds comment to .yaml + hyperlink to hardware description

* Update S6720-30C-EI-24S-AC.yaml

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Co-authored-by: Harry <Harry@cadby.co.uk>

device-types/Huawei/S6720-30C-EI-24S-AC.yaml

@@ -4,6 +4,12 @@ model: S6720-30C-EI-24S-AC
 slug: huawei-s6720-30c-ei-24s-ac
 u_height: 1
 is_full_depth: true
+weight: 9.8
+weight_unit: kg
+airflow: front-to-rear
+front_image: true
+rear_image: true
+comments: '[Huawei S6720-30C-EI-24S-AC Hardware Description](https://support.huawei.com/enterprise/en/doc/EDOC1000013621/fb0c31cc/s6720-30c-ei-24s-ac)'
 console-ports:
   - name: console0
     type: rj-45