Fix linter warnings

[oufmilo]

Problem

! scripts/install

! It looks like this app requires the admin to finish the install by entering DB credentials. Unless it's absolutely not easily automatizable, this should be handled automatically by the app install script using curl calls, or (CLI tools provided by the upstream maybe ?). 

Solution

Add ynh_send_readme_to_admin__2

PR Status

• [ ] Code finished and ready to be reviewed/tested
• [ ] The fix/enhancement were manually tested (if applicable)

Automatic tests

Automatic tests can be triggered on https://ci-apps-dev.yunohost.org/ after creating the PR, by commenting "!testme", "!gogogadgetoci" or "By the power of systemd, I invoke The Great App CI to test this Pull Request!". (N.B. : for this to work you need to be a member of the Yunohost-Apps organization)

[oufmilo]

!testme

[yunohost-bot]

:carousel_horse:

[ericgaspar]

This PR just seems to bypass the linter warning. I think I will prefer the warning to be addressed so we don't need to send credentials to email. (this will be less problematic with app v2).