message: [genesis] add variables
  Closes:
diff: @@ -63,6 +63,8 @@ The remainder of this section specifies distinct behaviors for each role.
  While `libra-genesis-tool` supports setting the backends on each command, doing so is cumbersome and fraught with error. Instead, all participants, should first construct a configuration file for use in genesis and later use via the operational tool. Below is an example configuration file in yaml format:
  ```
  +# config.yaml
  +
  chain_id: "MAINNET"
  json_server: "http://127.0.0.1:8080"
  shared_backend:
  @@ -94,7 +96,7 @@ Overview of fields:
  cargo run -p libra-genesis-tool -- \
  set-layout \
  --config config_file.yaml \
  - --path PATH_TO_LAYOUT ```
  + --path $PATH_TO_LAYOUT ```
  * The association will publish the the `libra root` public key to the `shared storage`:
  ```
  cargo run -p libra-genesis-tool -- \
  @@ -136,7 +138,7 @@ cargo run -p libra-genesis-tool -- \
  cargo run -p libra-genesis-tool --
  set-operator \
  --config config_file.yaml \
  - --operator-name OPERATOR_NAME
  + --operator-name $OPERATOR_NAME
  ```
  ### Validator Operators
  @@ -152,23 +154,23 @@ cargo run -p libra-genesis-tool --
  cargo run -p libra-genesis-tool --
  validator-config \
  --config config_file.yaml \
  - --owner-name OWNER_NAME \
  - --validator-address '/dns/DNS/tcp/PORT' \
  - --fullnode-address '/dns/DNS/tcp/PORT' \
  + --owner-name $OWNER_NAME \
  + --validator-address "/dns/$VALIDATOR_DNS/tcp/$VALIDATOR_PORT" \
  + --fullnode-address "/dns/$VFN_DNS/tcp/$VFN_PORT" \
  ```
  * Upon receiving signal from the association, OPs can now build genesis:
  ```
  cargo run -p libra-genesis-tool -- \
  genesis \
  --config config_file.yaml \
  - --path PATH_TO_GENESIS \
  + --path $PATH_TO_GENESIS \
  ```
  * Similarly, the association should publish a genesis waypoint, and the OP should insert it into their storage (using the management tool):
  ```
  cargo run -p libra-genesist-tool -- \
  insert-waypoint \
  --config config_file.yaml \
  - --waypoint WAYPOINT
  + --waypoint $WAYPOINT
  ```
  * Perform a verify that ensures the local store maps to Genesis and Genesis maps
  to the waypoint:
  @@ -176,7 +178,7 @@ cargo run -p libra-genesist-tool -- \
  cargo run -p libra-genesis-tool -- \
  verify \
  --config config_file.yaml \
  - --genesis_path PATH_TO_GENESIS
  + --genesis_path $PATH_TO_GENESIS
  ```
  ### Important Notes
  