docs: add reth migration docs #7255

Job	Run time
branch_name	4s
lint / yamllint	8s
lint / goreleaser-check	7s
lint / markdown-lint	1m 33s
test / Build ev-node Docker Image	15m 1s
test / Build All ev-node Binaries	2m 0s
test / Go Mod Tidy Check	42s
test / Build ev-node EVM Single Docker Image	14m 48s
lint / golangci-lint	34s
test / Run Unit Tests	4m 25s
test / Run Integration Tests	2m 54s
lint / hadolint / hadolint	8s
proto / buf-check	7s
test / Run EVM Execution Tests	2m 30s
test / Run E2E System Tests	7m 19s
test / Combine and Upload Coverage	0s
test / Docker E2E Tests	1m 33s
release	0s
	53m 53s

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