add notes on how to upgrade from 2.x to 3.0

Author: goetas

UPGRADE.md

@@ -0,0 +1,57 @@
+# Upgrade
+
+## From 2.x to 3.0.0
+
+- The configuration for the migration namespace and directory changed as follows:
+
+Before
+
+```yaml
+doctrine_migrations:
+    dir_name: '%kernel.project_dir%/src/Migrations'
+    namespace: DoctrineMigrations
+```
+
+After
+
+```yaml
+doctrine_migrations:
+    migrations_paths:
+        'DoctrineMigrations': '%kernel.project_dir%/src/Migrations'
+```
+
+- The configuration for the metadata table definition changed as follows:
+
+Before
+
+```yaml
+doctrine_migrations:
+    table_name: 'migration_versions'
+    column_name: 'version'
+    column_length: 14
+    executed_at_column_name: 'executed_at'
+```
+
+After
+
+```yaml
+doctrine_migrations:
+    storage:
+        table_storage:
+            table_name: 'migration_versions'
+            version_column_name: 'version'
+            version_column_length: 1024
+            executed_at_column_name: 'executed_at'
+```
+- The migration name has been dropped:
+
+Before
+
+```yaml
+doctrine_migrations:
+    name: 'Application Migrations'
+```
+
+After
+
+The parameter `name` has been dropped.