docs: fix typo in migrations doc (typeorm#9499)

Datasoure ==> Datasource

Author: karimmakhloufi

docs/migrations.md

@@ -238,7 +238,7 @@ module.exports = class PostRefactoringTIMESTAMP {
 See, you don't need to write the queries on your own.
 The rule of thumb for generating migrations is that you generate them after **each** change you made to your models. To apply multi-line formatting to your generated migration queries, use the `p` (alias for `--pretty`) flag.
 
-## DataSoure option
+## DataSource option
 
 If you need to run/revert/generate/show your migrations use the `-d` (alias for `--dataSource`) and pass the path to the file where your DataSource instance is defined as an argument