Add support for 2 more SSL certificate retrieval methods

Adds support for managing certificates manually and for
having the playbook generate self-signed certificates for you.

With this, Let's Encrypt usage is no longer required.

Fixes Github issue #50.

docs/configuring-playbook-ssl-certificates.md

@@ -0,0 +1,32 @@
+# Adjusting SSL certificate retrieval (optional, advanced)
+
+By default, this playbook retrieves and auto-renews free SSL certificates from [Let's Encrypt](https://letsencrypt.org/).
+
+If that's alright, you can skip this.
+
+
+## Using self-signed SSL certificates
+
+For private deployments (not publicly accessible from the internet), you may not be able to use Let's Encrypt certificates.
+
+If self-signed certificates are alright with you, you can ask the playbook to generate such for you with the following configuration:
+
+```yaml
+matrix_ssl_retrieval_method: self-signed
+```
+
+
+## Using your own SSL certificates
+
+If you'd like to manage SSL certificates by yourself and have the playbook use your certificate files, you can use the following configuration:
+
+```yaml
+matrix_ssl_retrieval_method: manually-managed
+```
+
+With such a configuration, the playbook would expect you to drop the SSL certificate files in the directory specified by `matrix_ssl_config_dir_path` (`/matrix/ssl/config` by default) obeying the following hierarchy:
+
+- `<matrix_ssl_config_dir_path>/live/<domain>/fullchain.pem`
+- `<matrix_ssl_config_dir_path>/live/<domain>/privkey.pem`
+
+where `<domain>` refers to the domains that you need (usually `matrix.<your-domain>` and `riot.<your-domain>`).