Docs for 0.2.0 are broken since #456 was merged two days ago

Docs are broken for 0.2.0 since https://github.com/apache/pulsar-manager/pull/456 was merged

Docs for 0.2.0 reference master branch sql script which creates the tables `roles` and `role_binding`, the [documentation](https://pulsar.apache.org/docs/administration-pulsar-manager/) says:

> Initialize database and table structures using the [file](https://github.com/apache/pulsar-manager/blob/master/src/main/resources/META-INF/sql/postgresql-schema.sql).

But that script no longer creates such tables, so users of 0.2.0 will get the following error:

```
{"timestamp":"2022-07-15T19:11:52.227+0000","status":500,"error":"Internal Server Error","message":"\n### Error querying database. Cause: org.postgresql.util.PSQLException: ERROR: relation \"roles\" does not exist\n Position: 220\n### The error may exist in org/apache/pulsar/manager/mapper/RolesMapper.java (best guess)\n### The error may involve org.apache.pulsar.manager.mapper.RolesMapper.findByRoleFlag-Inline\n### The error occurred while setting parameters\n### SQL: SELECT role_id AS roleId, role_name AS roleName, description, resource_type AS resourceType,resource_name AS resourceName, resource_verbs AS resourceVerbs, resource_id as resourceId,role_source AS roleSource, flag FROM roles WHERE flag=? limit 1\n### Cause: org.postgresql.util.PSQLException: ERROR: relation \"roles\" does not exist\n Position: 220\n; bad SQL grammar []; nested exception is org.postgresql.util.PSQLException: ERROR: relation \"roles\" does not exist\n Position: 220","path":"/pulsar-manager/users/superuser"}
```

\cc @tuteng @urfreespace