some minor readme updates

Signed-off-by: Sascha Wiswedel <sascha.wiswedel@nextcloud.com>

Signed-off-by: Roeland Jago Douma <roeland@famdouma.nl>

Signed-off-by: Daniel Kesselberg <mail@danielkesselberg.de>

Signed-off-by: Jan-Christoph Borchardt <hey@jancborchardt.net>

Signed-off-by: Jan-Christoph Borchardt <hey@jancborchardt.net>

Signed-off-by: Jan-Christoph Borchardt <hey@jancborchardt.net>

Signed-off-by: Jan-Christoph Borchardt <hey@jancborchardt.net>

Signed-off-by: Jan-Christoph Borchardt <hey@jancborchardt.net>

Signed-off-by: Jan-Christoph Borchardt <hey@jancborchardt.net>

Signed-off-by: Jan-Christoph Borchardt <hey@jancborchardt.net>

Signed-off-by: Jan-Christoph Borchardt <hey@jancborchardt.net>

Signed-off-by: Jan-Christoph Borchardt <hey@jancborchardt.net>

Signed-off-by: Christoph Wurst <christoph@winzerhof-wurst.at>

Written at the Nextcloud Conf workshop

Signed-off-by: Roeland Jago Douma <roeland@famdouma.nl>

authentification is not a real word :)

Signed-off-by: Morris Jobke <hey@morrisjobke.de>

- Removes the Drone badge
  - This one is lying most of the time since it isn't checking master but the latest build. Thus it fails when it effectively doesn't fail. Let's remove that since it makes us look bad.
- Add CodeCov badge
- Add CII badge

Signed-off-by: Lukas Reschke <lukas@statuscode.ch>

Signed-off-by: Joas Schilling <coding@schilljs.com>

Signed-off-by: Marius Blüm <marius@lineone.io>

Signed-off-by: Morris Jobke <hey@morrisjobke.de>

Per issue: https://github.com/nextcloud/server/issues/16
Added installation link guides per the already established documentation rather than attempting to re-create the documentation here.

It's production ready now.

add some information for contributors regarding the copyright header and claify that all contributions are considered AGPLv3 or later

Update the readme to refer to Nextcloud

`diffrent` → `different`