Add template and documentation on how to submit an new app / app update

[lukasschor]

What is this about?

• Template that includes fields for all relevant information in order to make a decision on whether to add/update an app and the information needed to actually make the addition
• Documentation on docs.gnosis.io/safe on how to add a Safe App to the Safe Apps List

Questions

• Should it be a ticket template or a PR template (i.e. do we want to create the actual PRs ourselves or have them created by external people)?

Why is this needed?

We anticipate many Safe Apps being added in the weeks and months to come. Also many apps might require an update to the entry in the Safe Apps List.

Currently, this results in a lot of coordination overhead as we have to create a ticket ourselves and collect all relevant data that is needed to have an app added/updated