Merge pull request getsops#564 from leitu/corret_readme

correct azure key environment in readme

README.rst

@@ -296,7 +296,7 @@ Adding and removing keys
 When creating new files, ``sops`` uses the PGP, KMS and GCP KMS defined in the
 command line arguments ``--kms``, ``--pgp``, ``--gcp-kms`` or ``--azure-kv``, or from
 the environment variables ``SOPS_KMS_ARN``, ``SOPS_PGP_FP``, ``SOPS_GCP_KMS_IDS``,
-``SOPS_AZURE_KEYVAULT_URL``. That information is stored in the file under the
+``SOPS_AZURE_KEYVAULT_URLS``. That information is stored in the file under the
 ``sops`` section, such that decrypting files does not require providing those
 parameters again.