chore(maindbv4): add a migration guide #910

Job	Run time
Lint / golangci-lint	1m 28s
License Check / license-check	32s
E2E Tests / Build Docker image	1m 52s
Go Module Check / ensure go mod is tidy	8s
Run Unit Tests / unit_tests (1.22.x, ubuntu-latest)	1m 34s
Run Unit Tests / unit_tests (1.22.x, macos-latest)	1m 35s
Test Docker Publish / Build and Push Docker Image	1m 39s
Run Unit Tests / test_coverage	3m 13s
Run Unit Tests / unit_tests (1.22.x, windows-latest)	4m 21s
Run Unit Tests / unit_tests (1.23.x, ubuntu-latest)	1m 38s
E2E Tests / Run Tests	4m 41s
	22m 41s

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