Chore: fix doc and refine variable names #314

Job	Run time
lint	13m 13s
openraft-feature-test (nightly)	50s
examples (stable, memstore)	41s
openraft-feature-test (nightly, serde)	1m 2s
cluster-benchmark (cluster_benchmark)	48s
examples (stable, raft-kv-memstore)	2m 38s
openraft-feature-test (nightly, single-term-leader)	48s
examples (stable, raft-kv-memstore-network-v2)	1m 3s
openraft-feature-test (nightly, single-term-leader,serde,singlethreaded)	55s
examples (stable, raft-kv-memstore-opendal-snapshot-data)	1m 34s
openraft-test (stable, 0)	3m 35s
examples (stable, raft-kv-memstore-singlethreaded)	1m 2s
openraft-test-bench (nightly)	56s
openraft-test (nightly, 30)	3m 31s
examples (stable, raft-kv-rocksdb)	8m 12s
stores (stores/memstore)	55s
openraft-test (nightly, 0, single-term-leader)	3m 23s
examples (nightly, memstore)	54s
stores (stores/rocksstore)	6m 20s
Build (nightly, bench,serde,bt,singlethreaded)	54s
examples (nightly, raft-kv-memstore)	2m 16s
stores (stores/sledstore)	1m 4s
examples (nightly, raft-kv-memstore-network-v2)	1m 26s
tests-feature-test (nightly)	3m 14s
examples (nightly, raft-kv-memstore-opendal-snapshot-data)	1m 52s
tests-feature-test (nightly, single-term-leader)	3m 4s
examples (nightly, raft-kv-memstore-singlethreaded)	1m 22s
tests-feature-test (nightly, loosen-follower-log-revert)	3m 14s
examples (nightly, raft-kv-rocksdb)	12m 48s
	1h 23m 34s

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