docs: Update UPDATING.md regarding potential breaking change to `ab_u…

…ser.email` column (#25115)

Co-authored-by: Michael S. Molina <70410625+michael-s-molina@users.noreply.github.com>

UPDATING.md

@@ -32,6 +32,7 @@ assists people when migrating to a new version.
 
 ## 3.0.0
 
+- [25053](https://github.com/apache/superset/pull/25053): Extends the `ab_user.email` column from 64 to 320 characters which has an associated unique key constraint. This will problematic for MySQL metadata databases which use the InnoDB storage engine with the `innodb_large_prefix` parameter disabled as the key prefix limit is 767 bytes. Enabling said parameter and ensuring that the table uses either the use the `DYNAMIC` or `COMPRESSED` row format should remedy the problem. See [here](https://dev.mysql.com/doc/refman/5.7/en/innodb-limits.html) for more details.
 - [24911](https://github.com/apache/superset/pull/24911): Changes the column type from `TEXT` to `MediumText` in table `logs`, potentially requiring a table lock on MySQL dbs or taking some time to complete on large deployments.
 - [24939](https://github.com/apache/superset/pull/24939): Augments the foreign key constraints for the `embedded_dashboards` table to include an explicit CASCADE ON DELETE to ensure the relevant records are deleted when a dashboard is deleted. Scheduled downtime may be advised.
 - [24938](https://github.com/apache/superset/pull/24938): Augments the foreign key constraints for the `dashboard_slices` table to include an explicit CASCADE ON DELETE to ensure the relevant records are deleted when a dashboard or slice is deleted. Scheduled downtime may be advised.

docs/docs/installation/configuring-superset.mdx

@@ -13,6 +13,7 @@ To configure your application, you need to create a file `superset_config.py` an
 `PYTHONPATH`. If your application was installed using docker-compose an alternative configuration is required. See [https://github.com/apache/superset/tree/master/docker#readme](https://github.com/apache/superset/tree/master/docker#readme) for details.
 
 The following is an example of just a few of the parameters you can set in your `superset_config.py` file:
+
 ```
 # Superset specific config
 ROW_LIMIT = 5000
@@ -72,7 +73,7 @@ WTF_CSRF_EXEMPT_LIST = [‘’]
 
 #### Adding an initial SECRET_KEY
 
-Superset requires a user-specified SECRET_KEY to start up.  This requirement was [added in version 2.1.0 to force secure configurations](https://preset.io/blog/superset-security-update-default-secret_key-vulnerability/).  Add a strong SECRET_KEY to your `superset_config.py` file like:
+Superset requires a user-specified SECRET_KEY to start up. This requirement was [added in version 2.1.0 to force secure configurations](https://preset.io/blog/superset-security-update-default-secret_key-vulnerability/). Add a strong SECRET_KEY to your `superset_config.py` file like:
 
 ```python
 SECRET_KEY = 'YOUR_OWN_RANDOM_GENERATED_SECRET_KEY'
@@ -83,7 +84,7 @@ You can generate a strong secure key with `openssl rand -base64 42`.
 #### Rotating to a newer SECRET_KEY
 
 If you wish to change your existing SECRET_KEY, add the existing SECRET_KEY to your `superset_config.py` file as
-`PREVIOUS_SECRET_KEY = `and provide your new key as `SECRET_KEY =`.  You can find your current SECRET_KEY with these
+`PREVIOUS_SECRET_KEY = `and provide your new key as `SECRET_KEY =`. You can find your current SECRET_KEY with these
 commands - if running Superset with Docker, execute from within the Superset application container:
 
 ```python
@@ -103,23 +104,21 @@ database engine on a separate host or container.
 
 Superset supports the following database engines/versions:
 
-| Database Engine                                           | Supported Versions                |
-| --------------------------------------------------------- | --------------------------------- |
-| [PostgreSQL](https://www.postgresql.org/)                 | 10.X, 11.X, 12.X, 13.X, 14.X      |
-| [MySQL](https://www.mysql.com/)                           | 5.X                               |
-
+| Database Engine                           | Supported Versions                 |
+| ----------------------------------------- | ---------------------------------- |
+| [PostgreSQL](https://www.postgresql.org/) | 10.X, 11.X, 12.X, 13.X, 14.X, 15.X |
+| [MySQL](https://www.mysql.com/)           | 5.7, 8.X                           |
 
 Use the following database drivers and connection strings:
 
-| Database                                  | PyPI package                      | Connection String                                                        |
-| ----------------------------------------- | --------------------------------- | ------------------------------------------------------------------------ |
-| [PostgreSQL](https://www.postgresql.org/) | `pip install psycopg2`            | `postgresql://<UserName>:<DBPassword>@<Database Host>/<Database Name>`   |
-| [MySQL](https://www.mysql.com/)           | `pip install mysqlclient`         | `mysql://<UserName>:<DBPassword>@<Database Host>/<Database Name>`        |
+| Database                                  | PyPI package              | Connection String                                                      |
+| ----------------------------------------- | ------------------------- | ---------------------------------------------------------------------- |
+| [PostgreSQL](https://www.postgresql.org/) | `pip install psycopg2`    | `postgresql://<UserName>:<DBPassword>@<Database Host>/<Database Name>` |
+| [MySQL](https://www.mysql.com/)           | `pip install mysqlclient` | `mysql://<UserName>:<DBPassword>@<Database Host>/<Database Name>`      |
 
 To configure Superset metastore set `SQLALCHEMY_DATABASE_URI` config key on `superset_config`
 to the appropriate connection string.
 
-
 ### Running on a WSGI HTTP Server
 
 While you can run Superset on NGINX or Apache, we recommend using Gunicorn in async mode. This