Change default room version to 10. Implements MSC3904 (#14111)

* Change Documentation to have v10 as default room version

* Change Default Room version to 10

* Add changelog entry for default room version swap

* Add changelog entry for v10 default room version in docs

* Clarify doc changelog entry

Co-authored-by: David Robertson <david.m.robertson1@gmail.com>

* Improve Documentation changes.

Co-authored-by: David Robertson <david.m.robertson1@gmail.com>

* Update Changelog entry to have correct format

Co-authored-by: David Robertson <david.m.robertson1@gmail.com>

* Update Spec Version to 1.5

* Only need 1 changelog.

* Fix test.

* Update "Changed in" line

Co-authored-by: David Robertson <david.m.robertson1@gmail.com>
Co-authored-by: Patrick Cloke <clokep@users.noreply.github.com>
Co-authored-by: Patrick Cloke <patrickc@matrix.org>

1 files changed, 3 insertions, 1 deletions

diff --git a/docs/usage/configuration/config_documentation.md b/docs/usage/configuration/config_documentation.md

index 3481e866f7..2883f76a26 100644
--- a/docs/usage/configuration/config_documentation.md
+++ b/docs/usage/configuration/config_documentation.md
@@ -295,7 +295,9 @@ Known room versions are listed [here](https://spec.matrix.org/latest/rooms/#comp
 For example, for room version 1, `default_room_version` should be set
 to "1".
 
-Currently defaults to "9".
+Currently defaults to ["10"](https://spec.matrix.org/v1.5/rooms/v10/).
+
+_Changed in Synapse 1.76:_ the default version room version was increased from [9](https://spec.matrix.org/v1.5/rooms/v9/) to [10](https://spec.matrix.org/v1.5/rooms/v10/).
 
 Example configuration:
 ```yaml