mariadb: MARIADB_ROOT_PASSWORD_HASH to set of manditory vars

Order the manditory MARIADB_ROOT_PASSWORD* by decreasing strength.

Add ref MARIADB_PASSWORD_HASH to MARIADB_ROOT_PASSWORD_HASH for setting
password.

mariadb/content.md

@@ -101,13 +101,13 @@ When you start the `%%IMAGE%%` image, you can adjust the initialization of the M
 
 From tag 10.2.38, 10.3.29, 10.4.19, 10.5.10 onwards, and all 10.6 and later tags, the `MARIADB_*` equivalent variables are provided. `MARIADB_*` variants will always be used in preference to `MYSQL_*` variants.
 
-One of `MARIADB_ROOT_PASSWORD`, `MARIADB_ALLOW_EMPTY_ROOT_PASSWORD`, or `MARIADB_RANDOM_ROOT_PASSWORD` (or equivalents, including `*_FILE`), is required. The other environment variables are optional.
+One of `MARIADB_RANDOM_ROOT_PASSWORD`, `MARIADB_ROOT_PASSWORD_HASH`, `MARIADB_ROOT_PASSWORD` or `MARIADB_ALLOW_EMPTY_ROOT_PASSWORD` (or equivalents, including `*_FILE`), is required. The other environment variables are optional.
 
 ### `MARIADB_ROOT_PASSWORD` / `MYSQL_ROOT_PASSWORD`, `MARIADB_ROOT_PASSWORD_HASH`
 
 This specifies the password that will be set for the MariaDB `root` superuser account. In the above example, it was set to `my-secret-pw`.
 
-In order to have no plaintext secret in the deployment, `MARIADB_ROOT_PASSWORD_HASH` can be used as it is just the hash of the password. The hash can be generated with `SELECT PASSWORD('bob')` as a SQL query.
+In order to have no plaintext secret in the deployment, `MARIADB_ROOT_PASSWORD_HASH` can be used as it is just the hash of the password. The hash can be generated with `SELECT PASSWORD('thepassword')` as a SQL query.
 
 ### `MARIADB_ALLOW_EMPTY_ROOT_PASSWORD` / `MYSQL_ALLOW_EMPTY_PASSWORD`
 
@@ -135,7 +135,9 @@ This variable allows you to specify the name of a database to be created on imag
 
 These are used in conjunction to create a new user and to set that user's password. Both user and password variables are required for a user to be created. This user will be granted all access ([corresponding to `GRANT ALL`](https://mariadb.com/kb/en/grant/#the-all-privileges-privilege)) to the `MARIADB_DATABASE` database.
 
-Do note that there is no need to use this mechanism to create the root superuser, that user gets created by default with the password specified by the `MARIADB_ROOT_PASSWORD` / `MYSQL_ROOT_PASSWORD` variable.
+See `MARIADB_ROOT_PASSWORD_HASH` above for how to get a password hash for `MARIADB_PASSWORD_HASH`.
+
+Do note that there is no need to use this mechanism to create the root superuser, that user gets created by default with the password specified by the `MARIADB_ROOT_PASSWORD*` variable.
 
 ### `MARIADB_INITDB_SKIP_TZINFO` / `MYSQL_INITDB_SKIP_TZINFO`