From 3edcda744e6cbf2e9044d3e1a65b96880ac0ce06 Mon Sep 17 00:00:00 2001
From: Kaviraj <kavirajkanagaraj@gmail.com>
Date: Tue, 5 Jan 2021 11:11:45 +0100
Subject: [PATCH] mention the use of `config.expand-env` flag in the doc.
 (#3078)

---
 docs/sources/configuration/_index.md | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/docs/sources/configuration/_index.md b/docs/sources/configuration/_index.md
index 6beaa09c02..cd3e871218 100644
--- a/docs/sources/configuration/_index.md
+++ b/docs/sources/configuration/_index.md
@@ -89,6 +89,8 @@ ${VAR:default_value}
 
 Where default_value is the value to use if the environment variable is undefined.
 
+Pass the `-config.expand-env` flag at the command line to enable this way of setting configs.
+
 ### Generic placeholders:
 
 - `<boolean>` : a boolean that can take the values `true` or `false`