Sync docs from Discourse (#511)

Co-authored-by: GitHub Actions <41898282+github-actions[bot]@users.noreply.github.com>

docs/explanation/e-users.md

@@ -11,8 +11,8 @@ There are two types of users in MySQL:
 The operator uses the following internal DB users:
 
 * `root` - the [initial/default](https://charmhub.io/mysql/docs/t-manage-passwords) MySQL user. Used for very initial bootstrap only.
-* `clusteradmin` - the user to manage entire MySQL InnoDB ClusterSet.
-* `serverconfig` - the user to manage local MySQL instance.
+* `clusteradmin` - the user to manage replication in the MySQL InnoDB ClusterSet.
+* `serverconfig` - the user that operates MySQL instances.
 * `monitoring` - the user for [COS integration](https://charmhub.io/mysql/docs/h-enable-monitoring).
 * `backups` - the user to [perform/list/restore backups](https://charmhub.io/mysql/docs/h-create-and-list-backups).
 * `mysql_innodb_cluster_#######` - the [internal recovery users](https://dev.mysql.com/doc/mysql-shell/8.0/en/innodb-cluster-user-accounts.html#mysql-innodb-cluster-users-created) which enable connections between the servers in the cluster. Dedicated user created for each Juju unit/InnoDB Cluster member.
@@ -87,16 +87,20 @@ To set a predefined password for the specific user, run:
 <a name="relation-users"></a>
 ## Relation/integration users explanations:
 
-The operator created a dedicated user for every application related/integrated with database. Those users are removed on the juju relation/integration removal request. However, DB data stays in place and can be reused on re-created relations (using new user credentials):
+The operator created a dedicated user for every application related/integrated with database.
+The username is composed by the relation ID and truncated uuid for the model, to ensure there is no
+username clash in cross model relations. Usernames are limited to 32 chars as per [MySQL limit](https://dev.mysql.com/doc/refman/8.0/en/user-names.html).
+Those users are removed on the juju relation/integration removal request. 
+However, DB data stays in place and can be reused on re-created relations (using new user credentials):
 
 ```shell
 mysql> select Host,User,account_locked from mysql.user where User like 'relation%';
-+------+------------+----------------+
-| Host | User       | account_locked |
-+------+------------+----------------+
-| %    | relation-8 | N              |
-| %    | relation-9 | N              |
-+------+------------+----------------+
++------+----------------------------+----------------+
+| Host | User                       | account_locked |
++------+----------------------------+----------------+
+| %    | relation-8_99200344b67b4e9 | N              |
+| %    | relation-9_99200344b67b4e9 | N              |
++------+----------------------------+----------------+
 2 row in set (0.00 sec)
 ```
 

docs/reference/r-revision-153.md

@@ -41,7 +41,7 @@ Canonical Data issues are now public on both [Jira](https://warthogs.atlassian.n
 * CLI mysql-shell updated to `8.0.36+dfsg-0ubuntu0.22.04.1~ppa4`
 * Backup tools xtrabackup/xbcloud is `8.0.35-30`
 * The Prometheus mysqld-exporter is `0.14.0-0ubuntu0.22.04.1~ppa2`
-* K8s charms [based on our ROCK OCI](https://github.com/canonical/charmed-mysql-rock) (Ubuntu LTS  `22.04.4`) revision `103`
+* K8s charms [based on our ROCK OCI](https://github.com/canonical/charmed-mysql-rock) (Ubuntu LTS  `22.04.4`) `mysql-image` resource-revision `111`
 * Principal charms support the latest Ubuntu 22.04 LTS only
 
 ## Technical notes

docs/reference/r-revision-180-181.md

@@ -8,8 +8,8 @@ Dear community,
 Canonical's newest Charmed MySQL K8s operator has been published in the [8.0/stable channel].
 
 Due to the newly added support for arm64 architecture, the MySQL K8s charm now releases two revisions simultaneously:
-* Revision 180 is built for `amd64`
-* Revision 181 is built for `arm64`
+* Revision 180 is built for `amd64` ( mysql-image  r113 )
+* Revision 181 is built for `arm64` ( mysql-image  r113 )
 
 TO make sure you deploy for the right architecture, we recommend setting an [architecture constraint](https://juju.is/docs/juju/constraint#heading--arch) for your entire Juju model.
 
@@ -60,7 +60,7 @@ This release of Charmed MySQL requires Juju `v.3.4.3` or `3.5.2+`. See the guide
 See the [system requirements] page for more details about software and hardware prerequisites.
 
 ### Packaging
-This charm is based on the [`charmed-mysql` rock]. It packages:
+This charm is based on the [`charmed-mysql` rock]  (CharmHub  `mysql-image` resource-revision `113`). It packages:
 - mysql-server-8.0 `v8.0.37`
   - [8.0.37-0ubuntu0.22.04.1]
 - mysql-router `v8.0.37`