docs: Create basic installation/configuration/usage

Signed-off-by: Julien Riou <julien@riou.xyz>

README.md

@@ -1,3 +1,42 @@
 # Ansible Role Forgejo
 
 Ansible role to manage a Forgejo instance.
+
+## Installation
+
+Clone the repository in your local Ansible role directory:
+
+```
+git clone https://git.riou.xyz/jriou/ansible-role-forgejo.git ~/.ansible/roles/forgejo
+```
+
+## Configuration
+
+See [Variable
+precedence](https://docs.ansible.com/ansible/latest/playbook_guide/playbooks_variables.html#ansible-variable-precedence)
+to find where you should put your own variables.
+
+Then define at least `forgejo_db_password` with a strong and secure password,
+encrypted using
+[ansible-vault](https://docs.ansible.com/ansible/latest/cli/ansible-vault.html).
+
+See list of [default variables](defaults/main.yml).
+
+
+## Usage
+
+Example of a basic forgejo.yml playbook:
+
+```yaml
+hosts:
+  - forgejo
+
+roles:
+  - forgejo
+```
+
+Then run the playbook:
+
+```
+ansible-playbook forgejo.yml
+```