Describe the bug
GitHub Provider when used as SecretStore or ClusterSecret supports PushSecret only or in an essentially one-way / write-only behavior. However, the documentation doesn't mention it and could lead to confusion.

To Reproduce

1. Create a SecretStore or ClusterSecret store as mentioned in the documentation:

apiVersion: external-secrets.io/v1
kind: ClusterSecretStore
metadata:
  name: gh
spec:
  provider:
    github:
      appID: 12345
      installationID: 67890
      organization: myorg
      repository: myrepo
      environment: myenv
      auth:
        privateKey:
          namespace: x
          name: y
          key: key

2. Create an ExternalSecret that references the SecretStore or ClusterSecretStore

apiVersion: external-secrets.io/v1
kind: ExternalSecret
metadata:
  name: test-secret
  namespace: myns
spec:
  data:
    - remoteRef:
        key: TEST_SECRET
      secretKey: test-secret
  refreshInterval: 1m
  secretStoreRef:
    kind: ClusterSecretStore
    name: gh
  target:
    creationPolicy: Owner
    name: test-secret

Expected behavior
The remote secret on GitHub should be successfully sync to the cluster.

Actual Behavior
The ExternalSecret object was created but with an sync error not implemented - this provider supports write-only operations

Additional context

The SecretStore / ClusterSecret store when created with the GitHub provider will have a the following status:

status:
  capabilities: WriteOnly

Even though one could read the GitHub API Documentation and see that there is no endpoint to fetch the actual secret value, the documentation of External Secrets regarding the GitHub provider should be updated to explicitly mention that the GitHub provider supports only write-only operations.