[DOC] Document ISM transition conditions `no_alias` and `min_state_age`

[Tarun-kishore]

The PR #1440 introduces two new transition conditions in Index State Management (ISM):

• no_alias (boolean):
  Enables transitions based on whether the index is currently associated with any alias.

  • true: transition only if the index has no aliases
  • false: transition only if the index has one or more aliases

• min_state_age (string duration, e.g., "7d"):
  Allows a transition to happen only after the index has spent the specified time in its current ISM state.

Changes are required in ISM documentation to add details about these new conditions.

Related PR: opensearch-project/index-management#1440
Target Release: 3.2

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Version: 3.2 and above

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