Reformatting README for Terraform Registry

Hi there,

renamed the path of the source to the module registry instead of the GitHub repo

removed variables because all variable information is sourced from the variable and output files.

If you can merge this into master and then add another release/tag so that the module registry will update. After that we'll be able to verify this module.

Thanks
Chris

Author: Chris Griggs

README.md

@@ -8,46 +8,12 @@ See the Cloud SQL documentation for details: https://cloud.google.com/sql
 
 ```ruby
 module "mysql-db" {
-  source           = "github.com/GoogleCloudPlatform/terraform-google-sql-db"
+  source           = "GoogleCloudPlatform/sql-db/google"
   name             = "example-mysql-${random_id.name.hex}"
   database_version = "MYSQL_5_6"
 }
 ```
 
-### Input variables
-
-- `project` (optional): The project to deploy to, if not set the default provider project is used.
-- `region` (optional): Region for cloud resources. Default is `us-central1`.
-- `name` (required): Name for the database instance. Must be unique and cannot be reused for up to one week.
-- `database_version` (optional): The version of of the database. For example, `MYSQL_5_6` or `POSTGRES_9_6`. Default is `MYSQL_5_6`.
-- `tier` (optional): The machine tier (First Generation) or type (Second Generation). See this page for supported tiers and pricing: https://cloud.google.com/sql/pricing. Default is `db-f1-micro`.
-- `db_name` (optional): Name of the default database to create. Default is `default`.
-- `db_charset` (optional): The charset for the default database. Default is `""` which will revert to the default for the database version.
-- `db_collation` (optional): The collation for the default database. Example for MySQL databases: 'utf8', and Postgres: 'en_US.UTF8'". Default is `""` which will revert to the default for the database version.
-- `user_name` (optional): The name of the default user. Default is `default`.
-- `user_host` (optional): The host for the default user. Default is `"%"`. Set to `""` if database version is PostgreSQL.
-- `user_password` (optional): "The password for the default user. If not set, a random one will be generated and available in the `generated_user_password` output variable.
-- `activation_policy` (optional): This specifies when the instance should be active. Can be either `ALWAYS`, `NEVER` or `ON_DEMAND.`
-- `authorized_gae_applications` (optional): A list of Google App Engine (GAE) project names that are allowed to access this instance. Default is `[]`.
-- `disk_autoresize` (optional): Second Generation only. Configuration to increase storage size automatically. Default is `true`.
-- `disk_size` (optional): Second generation only. The size of data disk, in GB. Size of a running instance cannot be reduced but can be increased. Default is `10`.
-- `disk_type` (optional): Second generation only. The type of data disk: `PD_SSD` or `PD_HDD`. Default is `PD_SSD`.
-- `pricing_plan` (optional): First generation only. Pricing plan for this instance, can be one of `PER_USE` or `PACKAGE`. Default is `PER_USE`.
-- `replication_type` (optional): Replication type for this instance, can be one of `ASYNCHRONOUS` or `SYNCHRONOUS`. Default is `SYNCHRONOUS`.
-- `backup_configuration` (optional): The backup_configuration settings subblock for the database setings. Default is `{}`
-- `ip_configuration` (optional): The ip_configuration settings subblock. Default is `[{}]`.
-- `location_preference` (optional): The location_preference settings subblock. Default is `[]`.
-- `maintenance_window` (optional): The maintenance_window settings subblock. Defualt is `[]`.
-- `replica_configuration` (optional): The optional replica_configuration block for the database instance. Default is `[]`.
-
-### Output variables 
-
-- `instance_name`: The name of the database instance.
-- `instance_address`: The IPv4 address of the master database instnace.
-- `instance_address_time_to_retire`: The time the master instance IP address will be reitred. RFC 3339 format.
-- `self_link`: Self link to the master instance.
-- `generated_user_password`: The auto generated default user password if no input password was provided.
-
 ## Resources created
 
 - [`google_sql_database_instance.master`](https://www.terraform.io/docs/providers/google/r/sql_database_instance.html): The master database instance.