Add proper documentation to yunohost homepage

[rndmh3ro]

Describe the bug

There should be a proper documentation here: https://yunohost.org/en/app_invoiceninja5

Things to document aside from the usual stuff:

api_secret usage

From https://forum.yunohost.org/t/invoice-ninja-5-ready-for-usage/18743/4:

It was not easy to understand that there is an existing API_SECRET value (which is asked when logging in but marked as ‘optional’), and it was not easy to find it.

"public" usage

See: https://forum.yunohost.org/t/server-error-trying-to-use-the-linux-snap-invoiceninja-app/19479/2

The app was not set as “public” in the Yunohost group and permissions settings. It took me a while to realize that as I’m always logged in my Yunohost account usually. But when I tested in a isolated tab I realized I was redirected to the Yunohost login page first and understood that was probably the problem. This is probably something interesting to state in the documentation.

[fflorent]

api_secret usage

I had the same issue. Maybe worth to send email on installation with the instructions for login? (like other applications do like PeerTube_ynh)

See:

• the instruction on installation for PeerTube: https://github.com/YunoHost-Apps/peertube_ynh/blob/9bf92ff65db0dcb188834738f180dbfa34ebef09/scripts/install#L288
• the helper source to include in the package : https://github.com/YunoHost-Apps/peertube_ynh/blob/9bf92ff65db0dcb188834738f180dbfa34ebef09/scripts/ynh_send_readme_to_admin__2

[rndmh3ro]

Good idea. Pull Requests are welcomed!

[fflorent]

In progress ;-)

[yalh76]

PR merged to master