[PATCH backup v2 2/3] docs: client: document further password constrains

[Maximiliano Sandoval <m.sandoval@proxmox.com>]

We leave the explicit newlines as "control character" might not mean
much anything to some readers.

Signed-off-by: Maximiliano Sandoval <m.sandoval@proxmox.com>
---
 docs/backup-client.rst | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/docs/backup-client.rst b/docs/backup-client.rst
index 40962f0e2..03a383d9c 100644
--- a/docs/backup-client.rst
+++ b/docs/backup-client.rst
@@ -104,9 +104,10 @@ Environment Variables
    wireguard, instead of using an HTTP proxy.
 
 
-.. Note:: Passwords must be valid UTF-8 and may not contain newlines. For your
-   convenience, Proxmox Backup Server only uses the first line as password, so
-   you can add arbitrary comments after the first newline.
+.. Note:: Passwords must be valid UTF-8 and may not contain newlines or any
+   control characters in general. For your convenience, Proxmox Backup Server
+   only uses the first line as password, so you can add arbitrary comments after
+   the first newline.
 
 
 System and Service Credentials
-- 
2.47.3