grammar fix

README.md

@@ -17,7 +17,7 @@ acme-downloader --vault-token=<VAULT-TOKEN> --redis-token=<REDIS_TOKEN> \
     --cert-name=foo-ev-cert.geant.org --team-name=swd
 ```
 
- or check all the option using `--help`:
+ or check all the options using `--help`:
 
 ```bash
 ACME Downloader: