add documentation for temporary_enrollemnt_source_user_id

Documentation about the new column in the SIS import

closes FOO-4547
flag=none

test-plan:
- render docs

Change-Id: I3572d4059165fb89ef0cb37bceb3c00061c163ca
Reviewed-on: https://gerrit.instructure.com/c/canvas-lms/+/351185
Reviewed-by: August Thornton <august@instructure.com>
QA-Review: Maya Tyner <maya.tyner@instructure.com>
Product-Review: Maya Tyner <maya.tyner@instructure.com>
Tested-by: Service Cloud Jenkins <svc.cloudjenkins@instructure.com>

doc/api/sis_csv.md

@@ -799,6 +799,15 @@ Ignored for any role other than observer</td>
 <td>If true, a notification will be sent to the enrolled user. Notifications are
  not sent by default. </td>
 </tr>
+<tr>
+<td>temporary_enrollment_source_user_id</td>
+<td>text</td>
+<td></td>
+<td></td>
+<td>The User identifier from users.csv of a provider in a temporary enrollment.
+ If included, the created enrollment is a temporary enrollment.
+ <em>Requires Temporary Enrollments feature option.</em></td>
+</tr>
 </table>
 
 &#42; course_id or section_id is required, role or role_id is required, and