Create ED2 user guide

[zhang4952]

Descriptive summary

Create documentations of ED2 design and deposit process for users, the outcome will be

• used for the article recruit email
• used as user help at different ED2 steps

[zhang4952]

https://docs.google.com/document/d/1Tn_W25gaYYpqL5V20YjzCXp9AXMjhpl72OUqpy4-e3c/edit#

[zhang4952]

• [x] Create draft (see link above) and collect feedbacks

• [x] Update ED2 views to use language in the documentation as help

[zhang4952]

fixed by #179 - #181