Use versionless migrations URL for site-book redirect

Follow-up to #8230 per josbeir's suggestion.

Author: dereuromark

docs/en/contents.md

@@ -63,7 +63,7 @@
 - [Authorization](https://book.cakephp.org/authorization/3/)
 - [Bake](https://book.cakephp.org/bake/3/)
 - [Debug Kit](https://book.cakephp.org/debugkit/5/)
-- [Migrations](https://book.cakephp.org/migrations/5/)
+- [Migrations](https://book.cakephp.org/migrations/)
 - [Elasticsearch](https://book.cakephp.org/elasticsearch/4/)
 - [Phinx](https://book.cakephp.org/phinx/0/en/)
 - [Chronos](https://book.cakephp.org/chronos/3/)

docs/en/migrations.md

@@ -1,3 +1,3 @@
 # Migrations
 
-This page has [moved](https://book.cakephp.org/migrations/5/).
+This page has [moved](https://book.cakephp.org/migrations/).

docs/en/tutorials-and-examples/cms/database.md

@@ -321,7 +321,7 @@ conventions will save you time as you can leverage the convention-based defaults
 CakePHP provides.
 
 ::: tip Learn More
-Read more about database migrations and seeding in the [Migrations documentation](https://book.cakephp.org/migrations/5/).
+Read more about database migrations and seeding in the [Migrations documentation](https://book.cakephp.org/migrations/).
 :::
 
 With the database built, we can now build our [Models](../../tutorials-and-examples/cms/articles-model).

docs/ja/contents.md

@@ -64,7 +64,7 @@
 - [Authorization](https://book.cakephp.org/authorization/2/)
 - [Bake](https://book.cakephp.org/bake/2/ja/)
 - [Debug Kit](https://book.cakephp.org/debugkit/4/ja/)
-- [Migrations](https://book.cakephp.org/migrations/5/)
+- [Migrations](https://book.cakephp.org/migrations/)
 - [Elasticsearch](https://book.cakephp.org/elasticsearch/3/ja/)
 - [Phinx](https://book.cakephp.org/phinx/0/ja/)
 - [Chronos](https://book.cakephp.org/chronos/2/ja/)

docs/ja/migrations.md

@@ -1,3 +1,3 @@
 # Migrations
 
-このページは [移動しました](https://book.cakephp.org/migrations/5/) 。
+このページは [移動しました](https://book.cakephp.org/migrations/) 。