Update DEVICE_EXPOSURE.md

added visit_detail_id

https://github.com/OHDSI/CommonDataModel/issues/70

Documentation/CommonDataModel_Wiki_Files/StandardizedClinicalDataTables/DEVICE_EXPOSURE.md

@@ -16,6 +16,7 @@ Field|Required|Type|Description
 |visit_occurrence_id|No|integer|A foreign key to the visit in the VISIT table during which the device was used.|
 |device_source_value|No|varchar(50)|The source code for the Device as it appears in the source data. This code is mapped to a standard Device Concept in the Standardized Vocabularies and the original code is stored here for reference.|
 |device_source_ concept_id|No|integer|A foreign key to a Device Concept that refers to the code used in the source.|
+|visit_detail_id|No|integer|A foreign key to the visit in the visit-detail table during which the Drug Exposure was initiated.|
 
 ### Conventions 
 
@@ -24,4 +25,4 @@ Field|Required|Type|Description
   * Valid Device Concepts belong to the "Device" domain.  The Concepts of this domain are derived from the DI portion of a UDI or based on other source vocabularies, like HCPCS.
   * A Device Type is assigned to each Device Exposure to track from what source the information was drawn or inferred. The valid domain_id for these Concepts is "Device Type".
   * The Visit during which the Device was first used is recorded through a reference to the VISIT_OCCURRENCE table. This information is not always available.
-  * The Provider exposing the patient to the Device is recorded through a reference to the PROVIDER table. This information is not always available.
+  * The Provider exposing the patient to the Device is recorded through a reference to the PROVIDER table. This information is not always available.