Merge pull request #3307 from metabase/fix-docs-saying-only-postgres-on-rds

Fix docs saying only Postgres is supported on RDS.  [ci skip]

docs/operations-guide/running-metabase-on-elastic-beanstalk.md

-> **Covered in this guide:**  
-> [Installing Metabase on AWS Elastic Beanstalk](#running-metabase-on-aws-elastic-beanstalk)  
-> [Upgrading to new versions of Metabase](#deploying-new-versions-of-metabase)  
-> [Retaining Metabase logs on S3](#retaining-metabase-logs)  
-> [Running Metabase over HTTPS](#running-metabase-over-https)  
-> [Setting the Java timezone](#setting-the-jvm-timezone)  
-> [Using Papertrail for logging](#running-metabase-with-papertrail-on-aws)  
+**Covered in this guide:**
+
+> [Installing Metabase on AWS Elastic Beanstalk](#running-metabase-on-aws-elastic-beanstalk)
+> [Upgrading to new versions of Metabase](#deploying-new-versions-of-metabase)
+> [Retaining Metabase logs on S3](#retaining-metabase-logs)
+> [Running Metabase over HTTPS](#running-metabase-over-https)
+> [Setting the Java timezone](#setting-the-jvm-timezone)
+> [Using Papertrail for logging](#running-metabase-with-papertrail-on-aws)
 > [Protecting invalid hostname access](#protecting-against-invalid-hostname-access)
 
 
@@ -120,8 +121,8 @@ If you clicked the checkbox to create an RDS instance you will come to this sect
 
 Here you'll make the appropriate choices to configure your RDS database to work with Metabase.  Again, we cover each choice one-by-one:
 
-* `Snapshot` should be left as None.
-* `DB engine` must be set to `postgres`.  Currently this is the only RDS database type that Metabase supports.
+* `Snapshot` should be left as `None`.
+* `DB engine` should be set to `postgres`. Metabase also supports MySQL/Maria DB as backing databases, but this guide currently only covers running Metabase on Postgres.
 * `DB engine version` can simply be left on the default, which should be the latest version.
 * For `Instance class` you can choose any size, we recommend `db.t2.small` or bigger for production installs.  Metabase is pretty efficient so there is no need to make this a big instance.
 * You can safely leave `Allocated storage` to the default size.

docs/operations-guide/start.md

 
-**Covered in this guide:**  
-> [How to install Metabase](#installing-and-running-metabase)  
-> [How to upgrade Metabase](#upgrading-metabase)  
-> [Tips for troubleshooting various issues](#troubleshooting-common-problems)   
-> [Configuring the application database](#configuring-the-metabase-application-database)  
-> [Migrating from using the H2 database to MySQL or Postgres](#migrating-from-using-the-h2-database-to-mysql-or-postgres)  
-> [Running database migrations manually](#running-metabase-database-migrations-manually)  
-> [Backing up Metabase Application Data](#backing-up-metabase-application-data)  
-> [Customizing the Metabase Jetty Webserver](#customizing-the-metabase-jetty-webserver)  
-> [Changing password complexity](#changing-metabase-password-complexity)  
+**Covered in this guide:**
+
+> [How to install Metabase](#installing-and-running-metabase)
+> [How to upgrade Metabase](#upgrading-metabase)
+> [Tips for troubleshooting various issues](#troubleshooting-common-problems)
+> [Configuring the application database](#configuring-the-metabase-application-database)
+> [Migrating from using the H2 database to MySQL or Postgres](#migrating-from-using-the-h2-database-to-mysql-or-postgres)
+> [Running database migrations manually](#running-metabase-database-migrations-manually)
+> [Backing up Metabase Application Data](#backing-up-metabase-application-data)
+> [Customizing the Metabase Jetty Webserver](#customizing-the-metabase-jetty-webserver)
+> [Changing password complexity](#changing-metabase-password-complexity)
 > [Handling Timezones](#handling-timezones-in-metabase)
 
 # Installing and Running Metabase
@@ -205,9 +206,9 @@ If you launched Metabase on a laptop or PC the application will create an embedd
 NOTE: If your Metabase is currently running it's best to shut down the Metabase process before making a backup copy of the file.  Then, restart the application.
 
 ### Amazon RDS for the Database Application
-Amazon has its own best practices on how to backup and restore RDS databases, so we'll defer to them.  We recommend that you enable automated RDS Backups.  
+Amazon has its own best practices on how to backup and restore RDS databases, so we'll defer to them.  We recommend that you enable automated RDS Backups.
 
-Instructions can be found in the [Amazon RDS User Guide](http://docs.aws.amazon.com/AmazonRDS/latest/UserGuide/USER_WorkingWithAutomatedBackups.html).  
+Instructions can be found in the [Amazon RDS User Guide](http://docs.aws.amazon.com/AmazonRDS/latest/UserGuide/USER_WorkingWithAutomatedBackups.html).
 
 ### Self-managed PostgreSQL or MySQL database
 Simply follow the same instructions you would use for making any normal database backup.  It's a large topic more fit for a DBA to answer, but as long as you have a dump of the Metabase database you'll be good to go.