Better missing `secret_key_base` error message

Previously the error was:

```
RuntimeError: You must set secret_key_base in your app's config
```

Will now be:


```
RuntimeError: Missing `secret_key_base` for 'production' environment, set this value in `config/secrets.yml`
```

1 files changed, 1 insertions, 1 deletions

diff --git a/railties/lib/rails/application.rb b/railties/lib/rails/application.rb
index 5b20c178eb..05acd78d98 100644
--- a/railties/lib/rails/application.rb
+++ b/railties/lib/rails/application.rb
@@ -414,7 +414,7 @@ module Rails
 
     def validate_secret_key_config! #:nodoc:
       if secrets.secret_key_base.blank? && config.secret_token.blank?
-        raise "You must set secret_key_base in your app's config"
+        raise "Missing `secret_key_base` for '#{Rails.env}' environment, set this value in `config/secrets.yml`"
       end
     end
   end