Revise upgrade path documentation

- Final patch release for 12.0 is 12.0.12, not 12.0.9
- Clarify requirement to stop as at 12.0.x
- Make instruction broader to address future x.0.x releases.

doc/development/contributing/issue_workflow.md

@@ -80,6 +80,8 @@ already reserved for category labels).
 The descriptions on the [labels page](https://gitlab.com/groups/gitlab-org/-/labels)
 explain what falls under each type label.
 
+The GitLab handbook documents [when something is a bug and when it is a feature request.](https://about.gitlab.com/handbook/product/product-management/process/feature-or-bug.html)
+
 ### Facet labels
 
 Sometimes it's useful to refine the type of an issue. In those cases, you can

doc/policy/maintenance.md

@@ -127,7 +127,7 @@ one major version. For example, it is safe to:
   - `9.5.5` -> `9.5.9`
   - `10.6.3` -> `10.6.6`
   - `11.11.1` -> `11.11.8`
-  - `12.0.4` -> `12.0.9`
+  - `12.0.4` -> `12.0.12`
 - Upgrade the minor version:
   - `8.9.4` -> `8.12.3`
   - `9.2.3` -> `9.5.5`
@@ -144,9 +144,10 @@ It's also important to ensure that any background migrations have been fully com
 before upgrading to a new major version. To see the current size of the `background_migration` queue,
 [Check for background migrations before upgrading](../update/README.md#checking-for-background-migrations-before-upgrading).
 
-To ensure background migrations are successful, increment by one minor version during the version jump before installing newer releases.
+From version 12 onwards, an additional step is required. More significant migrations may occur during major release upgrades. To ensure these are successful, increment to the first minor version (`x.0.x`) during the major version jump. Then proceed with upgrading to a newer release.
+
+For example: `11.11.x` -> `12.0.x` -> `12.8.x`
 
-For example: `11.11.x` -> `12.0.x`
 Please see the table below for some examples:
 
 | Latest stable version | Your version | Recommended upgrade path | Note |
@@ -154,7 +155,8 @@ Please see the table below for some examples:
 | 9.4.5                 | 8.13.4       | `8.13.4` -> `8.17.7` -> `9.4.5`                          | `8.17.7` is the last version in version `8` |
 | 10.1.4                | 8.13.4       | `8.13.4 -> 8.17.7 -> 9.5.10 -> 10.1.4`                   | `8.17.7` is the last version in version `8`, `9.5.10` is the last version in version `9` |
 | 11.3.4                | 8.13.4       | `8.13.4` -> `8.17.7` -> `9.5.10` -> `10.8.7` -> `11.3.4` | `8.17.7` is the last version in version `8`, `9.5.10` is the last version in version `9`, `10.8.7` is the last version in version `10` |
-| 12.5.8                | 11.3.4       | `11.3.4` -> `11.11.8` -> `12.0.9` -> `12.5.8`            | `11.11.8` is the last version in version `11` |
+| 12.5.8                | 11.3.4       | `11.3.4` -> `11.11.8` -> `12.0.12` -> `12.5.8`            | `11.11.8` is the last version in version `11`. `12.0.x` [is a required step.](https://gitlab.com/gitlab-org/gitlab/-/merge_requests/23211#note_272842444) |
+| 12.8.5                | 9.2.6       | `9.2.6` -> `9.5.10` -> `10.8.7` -> `11.11.8` -> `12.0.12` -> `12.8.5` | Four intermediate versions required: the final 9.5, 10.8, 11.11 releases, plus 12.0 |
 
 More information about the release procedures can be found in our
 [release documentation](https://gitlab.com/gitlab-org/release/docs). You may also want to read our