document allowParallelRun

Author: angryziber

jobs/README.md

@@ -3,6 +3,9 @@
 Provides an ExecutorService-based JobRunner that also handles transactions.
 Depends on [jdbc module](../jdbc).
 
+By default, [Jobs](src/JobRunner.kt) use DB locks to ensure only one instance is running at a time.
+You can enable parallel runs by overriding `allowParallelRun` property.
+
 Usage example:
 ```kotlin
   use<JobRunner>().apply {