README: update with block import examples

Fix some heading along the way.

README.md

@@ -69,6 +69,8 @@ Build the **neo-go** CLI:
 make build
 ```
 
+### Running
+
 Quick start a NEO node on the private network. This requires the [neo-privatenet](https://hub.docker.com/r/cityofzion/neo-privatenet/) Docker image running on your machine.
 
 ```
@@ -92,6 +94,20 @@ Available network flags:
 - `--privnet, -p`
 - `--testnet, -t`
 
+#### Importing mainnet/testnet dump files
+
+If you want to jump-start your mainnet or testnet node with [chain archives
+provided by NGD](https://sync.ngd.network/) follow these instructions (when
+they'd be available for 3.0 networks):
+```
+$ wget .../chain.acc.zip # chain dump file
+$ unzip chain.acc.zip
+$ ./bin/neo-go db restore -m -i chain.acc # for testnet use '-t' flag instead of '-m'
+```
+
+The process differs from the C# node in that block importing is a separate
+mode, after it ends the node can be started normally.
+
 ## Smart contract development
 
 Please refer to [neo-go smart contract development
@@ -114,7 +130,7 @@ In `config/protocol.*.yml` there is
 ```
 where you can switch on/off and define port. Prometheus is enabled and Pprof is disabled by default.
 
-# Contributing
+## Contributing
 
 Feel free to contribute to this project after reading the
 [contributing guidelines](CONTRIBUTING.md).