message: 1. Staging readme update.
diff: @@ -3,15 +3,15 @@ In order to run a localised staged scenarios:
  1. Set staging root folder + settings file.
  ```
  -nctl-stage-init-settings stage=N
  +nctl-stage-init-settings stage=${X:-1}
  ```
  -NOTE: stage identifer N is assumed to be an unsigned integer.
  +NOTE: stage identifer X is assumed to be an unsigned integer.
  2. Build staged assets.
  ```
  -nctl-stage-build-from-settings stage=N
  +nctl-stage-build-from-settings stage=${X:-1}
  ```
  3. Review staged assets.
  @@ -27,12 +27,12 @@ $NCTL/staging/X_Y_Z/config
  4. Start network.
  ```
  -nctl-assets-setup-from-stage stage=N
  +nctl-assets-setup-from-stage stage=${X:-1}
  nctl-start
  ```
  5. Apply next upgrade.
  ```
  -nctl-assets-upgrade-from-stage stage=N
  +nctl-assets-upgrade-from-stage stage=${X:-1} era=${Y:-$(($(get_next_era) + 1))}
  ```
  