docs: add docs for BSC key management (#261)

* docs: add docs for BSC key management

* fix review comments

* fix review comments

docs/bcfusion/validators/key-managment.md

@@ -0,0 +1,54 @@
+# Key Management for BSC Validators
+
+[BEP-294](https://github.com/bnb-chain/BEPs/pull/294) and [BEP-297](https://github.com/bnb-chain/BEPs/pull/297)
+introduce the native staking and governance features for BNB Smart Chain (BSC). For a validator, when participating in
+staking (e.g., creating a validator, self-delegating) and governance, there are several wallet keys that will be
+involved. To help validators manage their keys and funds effectively and safely, the following practices are
+recommended.
+
+## Operator Key
+
+The operator key is used for operating a validator, including creating a validator, editing the information of a
+validator, and undelegating. When creating a validator, the operator key is also used for self-delegating with more than
+2001 BNB. When interacting with the new BSC staking dApp, the operator key is mostly involved.
+
+Be noted that the operator address can not be changed for a validator.
+
+**Recommendation: Use a hardware wallet, a Safe wallet or an MPC wallet; when creating validators, there should be more
+than 2001 BNB in
+the operator account.**
+
+## Staking Key
+
+For a validator, it can also use another key, different from the operator key, to manage his/her delegation if needed.
+Then, such a staking key will be used to delegate/undelegate/redelegate to different validators and claim rewards.
+This key could be used frequently, depending on how a validator manages its delegations and rewards.
+
+Be noted that this key is optional, depending on the needs of a validator.
+
+**Recommendation: Use a hardware wallet, a Safe wallet or an MPC wallet.**
+
+## Consensus Key
+
+The consensus key is used for signing proposed blocks when mining blocks. No fund is needed for this account.
+
+**Recommendation: Use a hot wallet so that it can be easily accessed by a validator node.**
+
+## Fast Finality Vote Key
+
+The fast finality vote key (BLS vote key) is used in
+the [fast finality feature](https://github.com/bnb-chain/BEPs/blob/master/BEPs/BEP126.md) for signing votes of recently
+mined blocks. No fund is needed for this account.
+
+**Recommendation: Use a hot wallet so that it can be easily accessed by a validator node.**
+
+## Governance Vote Key
+
+The [BEP-297](https://github.com/bnb-chain/BEPs/pull/297) introduces the native BSC staking feature.
+A delegator (including validators for self-delegation) can delegate someone else to participate in governance on his/her
+behalf. When there is governance delegation, the governance vote key will be used for casting votes to BSC proposals.
+The related wallet should store some BNB for gas fees of the voting transaction.
+
+Be noted that this key is optional, depending on the needs of a validator.
+
+**Recommendation: Use a hardware wallet, a Safe wallet or an MPC wallet.**