Add TRIPCODE_SALT setting to settings example

Signed-off-by: Alek Ratzloff <alekratz@gmail.com>

threadchat/settings.example.py

@@ -143,6 +143,9 @@ STATIC_ROOT = "static/"
 # Default primary key field type
 # https://docs.djangoproject.com/en/4.0/ref/settings/#default-auto-field
 
+# Tripcode salt to use. Should be reasonably random.
+TRIPCODE_SALT = env("TRIPCODE_SALT")
+
 # X-Frame-Options header from XFrameOptionsMiddleware
 X_FRAME_OPTIONS = "SAMEORIGIN"