Update api-overview.md (external-secrets#1361)

docs/api-overview.md

@@ -15,7 +15,7 @@ the cluster and update the secrets accordingly.
 ## Resource model
 
 To understand the mechanics of the operator let's start with the data model. The
-SecretStore references an bucket of key/value pairs. But because every external
+SecretStore references a bucket of key/value pairs. But because every external
 API is slightly different this bucket may be e.g. an instance of an Azure
 KeyVault or a AWS Secrets Manager in a certain AWS Account and region. Please
 take a look at the provider documentation to see what the Bucket actually maps