Include SESSION_COOKIE_AGE in .env.example

Suggested-by: Alexey Skobkin <[email protected]>

.env.example

@@ -137,6 +137,10 @@ TWO_FACTOR_LOGIN_MAX_SECONDS=60
 # and AWS_S3_CUSTOM_DOMAIN (if used) are added by default.
 # Value should be a comma-separated list of host names.
 CSP_ADDITIONAL_HOSTS=
+
 # The last number here means "megabytes"
 # Increase if users are having trouble uploading BookWyrm export files.
-DATA_UPLOAD_MAX_MEMORY_SIZE = (1024**2 * 100)
+DATA_UPLOAD_MAX_MEMORY_SIZE = (1024**2 * 100)
+
+# Time before being logged out (in seconds)
+# SESSION_COOKIE_AGE=2592000   # current default: 30 days