Update Start-HistoricalSearch.md

From following bug, Phish is no longer works with EXO, and it's not clear 'TPSEmailPhish' is same or not. So requesting just deleting Phish parameter at the time.

Issue 4102723: [Customer Escalation] [RFC]: Looking to confirm if changes were made to the ReportType parameter on Start-HistoricalSearch

Author: TomonoriAbe

exchange/exchange-ps/exchange/Start-HistoricalSearch.md

@@ -114,7 +114,6 @@ The ReportType parameter specifies the type of historical search that you want t
 - DLP: Data Loss Prevention Report.
 - MessageTrace: Message Trace Report.
 - MessageTraceDetail: Message Trace Details Report.
-- Phish: Exchange Online Protection and Defender for Office 365 E-mail Phish Report.
 - SPAM: SPAM Detections Report.
 - Spoof: Spoof Mail Report.
 - TransportRule: Transport or Mail Flow Rules Report.