message: fix doc to use right value for fields filter
diff: //! // Create an informer for watching events about
  //! let informer = Informer::new(pods).params(
  //! ListParams::default()
  -//! .fields("metadata.name=my-container")
  +//! .fields("metadata.name=my-pod")
  //! .timeout(10),
  //! );
  //!
  