docs: update the branch name master to main in the docs (#1058) #3045

Job	Run time
dockerfile: lint	22s
Build docker image	2m 51s
Dependencies are up to date	1m 33s
Generated files are up to date	2m 3s
golang: lint	4m 8s
Go tests	17m 50s
kubernetes_resources: ./config/crd	1m 10s
documentation: lint	31s
kubernetes_resources: ./config/samples/harborcluster-minimal	8s
kubernetes_resources: ./config/samples/harborcluster-standard	8s
kubernetes_resources: ./config/samples/harborcluster-fullstack	8s
kubernetes_resources: ./config/rbac	53s
	31m 45s

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