Document uploader as change property

Signed-off-by: Edwin Kempin <ekempin@google.com>
Bug: Google b/233384278
Release-Notes: skip
Change-Id: Iad4be9d4b9efb912e023f4b639a7f40adb60ff00
diff --git a/Documentation/concept-changes.txt b/Documentation/concept-changes.txt
index 0444fab..6e76a8a 100644
--- a/Documentation/concept-changes.txt
+++ b/Documentation/concept-changes.txt
@@ -34,6 +34,11 @@
 |Owner
 |The contributor who created the change.
 
+|Uploader
+|The user that uploaded the current patch set (e.g. the user that executed the
+`git push` command, or the user that triggered the patch set creation through
+an action in the UI).
+
 |Assignee
 |The contributor responsible for the change. Often used when a change has
 mulitple reviewers to identify the individual responsible for final approval.