small typo (#663)

Signed-off-by: Jake Sanders <[email protected]>

Author: Jake Sanders

cmd/cosign/cli/verify_blob.go

@@ -74,7 +74,7 @@ EXAMPLES
   cosign verify-blob -key cosign.pub -signature $sig msg
 
   # verify a signature with public key provided by URL
-  cosign verify-dockerfile -key https://host.for/<FILE> -signature $sig msg
+  cosign verify-blob -key https://host.for/<FILE> -signature $sig msg
 
   # Verify a signature against a payload from another process using process redirection
   cosign verify-blob -key cosign.pub -signature $sig <(git rev-parse HEAD)