Add more info to README

This shuld be helpful for #547

README.md

@@ -1,3 +1,32 @@
 # Hellgate
 
-Проект, реализующий основные state processors проведения платежей.
+Core logic service for payment states processing.
+
+## Building
+
+We widelly use Thrift to define RPC protocols.
+So it needs to have [our Thrift compiler](https://github.com/rbkmoney/thrift) in PATH to build this service.
+The recommended way to achieve this is by using our [build image](https://github.com/rbkmoney/image-build-erlang).
+
+We are still experimenting on opening our build infrastructure so that you can use the explicit public registry setting for now.
+You can adjust this parameter by exporting the environment variable `REGISTRY`.
+
+### Сheatsheet
+
+To build the service image without access to the internal RBK.money registry:
+
+```shell
+REGISTRY=ghcr.io make submodules wc_release build_image
+```
+
+To compile:
+
+```shell
+REGISTRY=ghcr.io make submodules wc_compile
+```
+
+To run the service tests (you need either to have access to the internal RBK.money registry or to modify `docker-compose.sh`):
+
+```shell
+make wdeps_test
+```