docs: clarify session close vs delete semantics (upstream sync #599)#177

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copilot/sync-upstream-changes-c4886a91-010c-45c9-8dcc-6c8f8229fe9acopilot-community-sdk/copilot-sdk-java:copilot/sync-upstream-changes-c4886a91-010c-45c9-8dcc-6c8f8229fe9aCopy head branch name to clipboard