docs: Add missing --retries argument to README

Author: lukasbestle

README.rst

@@ -55,7 +55,7 @@ CLI Help output::
                   [--skip-assets-on [SKIP_ASSETS_ON ...]] [--attachments]
                   [--throttle-limit THROTTLE_LIMIT]
                   [--throttle-pause THROTTLE_PAUSE]
-                  [--exclude [EXCLUDE ...]]
+                  [--exclude [EXCLUDE ...]] [--retries MAX_RETRIES]
                   USER
 
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