Add upgrading instructions for the upcoming version

Author: rosa

UPGRADING.md

@@ -1,3 +1,19 @@
+# Upgrading to version 0.5.x
+This version includes a new migration to improve recurring tasks. To install it, just run:
+
+```bash
+$ bin/rails solid_queue:install:migrations
+```
+
+Or, if you're using a different database for Solid Queue:
+
+```bash
+$ bin/rails solid_queue:install:migrations DATABASE=<the_name_of_your_solid_queue_db>
+```
+
+And then run the migrations.
+
+
 # Upgrading to version 0.4.x
 This version introduced an _async_ mode to run the supervisor and have all workers and dispatchers run as part of the same process as the supervisor, instead of separate, forked, processes. Together with this, we introduced some changes in how the supervisor is started. Prior this change, you could choose whether you wanted to run workers, dispatchers or both, by starting Solid Queue as `solid_queue:work` or `solid_queue:dispatch`. From version 0.4.0, the only option available is:
 
@@ -26,7 +42,6 @@ the supervisor will run 1 dispatcher and no workers.
 
 
 # Upgrading to version 0.3.x
-
 This version introduced support for [recurring (cron-style) jobs](https://github.com/rails/solid_queue/blob/main/README.md#recurring-tasks), and it needs a new DB migration for it. To install it, just run:
 
 ```bash