Update CHANGELOG for v1.0.0 (#1650) #4086

Job	Run time
Build Apiserver, CLI Binaries and Docker Images	3m 24s
Python Client Test	1m 5s
Build Operator Binaries and Docker Images	6m 20s
Lint	1m 56s
Compatibility Test - 2.4.0	11m 21s
Compatibility Test - 2.5.0	10m 52s
Compatibility Test - 2.6.3	10m 42s
Compatibility Test - 1.13.0	6m 28s
Compatibility Test - 2.7.0	12m 46s
Compatibility Test - Nightly	19m 33s
	1h 24m 27s

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