Cleanup readme files in roles directories

The contents of the README files are no longer up to date.
Documentation for all roles is located below the docs directory.

README.md

-# Ansible role: Ceph OSD
+# Ansible role: ceph-osd
 
-This role bootstraps Ceph OSD(s).
-It can bootstrap dockerized Ceph OSD(s).
-
-# Requirements
-
-Nothing, it runs out of the box.
-
-# Role variables
-
-Have a look at: `defaults/main.yml`.
-
-## Mandatory variables
-
-Choose between the following scenario to configure your OSDs, **choose only one**:
-
-* `journal_collocation`
-* `raw_multi_journal`
-
-Then:
-
-* `devices`
-* `raw_journal_devices` (**only if** you activated `raw_multi_journal`)
-
-# Dependencies
-
-The role `leseb.ceph-common` must be installed.
-
-# Example Playbook
-
-```
-- hosts: servers
-  remote_user: ubuntu
-  roles:
-     - { role: leseb.ceph-osd }
-```
-
-# Contribution
-
-**THIS REPOSITORY DOES NOT ACCEPT PULL REQUESTS**
-**PULL REQUESTS MUST GO THROUGH [CEPH-ANSIBLE](https://github.com/ceph/ceph-ansible)**
-
-# License
-
-Apache
-
-# Author Information
-
-This role was created by [Sébastien Han](http://sebastien-han.fr/).
+Documentation is available at http://docs.ceph.com/ceph-ansible/.