Update url.md

Adding clarification about needed permission

Author: pakud

docs/en/sql-reference/table-functions/url.md

@@ -78,6 +78,11 @@ SELECT * from url('http://data/path/date=*/country=*/code=*/*.parquet') where _d
 - [engine_url_skip_empty_files](/operations/settings/settings.md#engine_url_skip_empty_files) - allows to skip empty files while reading. Disabled by default.
 - [enable_url_encoding](/operations/settings/settings.md#enable_url_encoding) - allows to enable/disable decoding/encoding path in uri. Enabled by default.
 
+## Permissions
+
+`url` function requires `CREATE TEMPORARY TABLE` permission. As such - it'll not work for users with [readonly](/operations/settings/permissions-for-queries#readonly) = 1 setting. At least readonly = 2 is required.
+
+
 **See Also**
 
 - [Virtual columns](/engines/table-engines/index.md#table_engines-virtual_columns)