odissey: add build instructions to README.md
**odissey**
PostgreSQL connection pooler and request router.
+
+**build instructions**
+
+```sh
+git clone --recursive git://github.yandex-team.ru/pmwkaa/odissey.git
+cd odissey
+mkdir build
+cd build
+cmake ..
+make
+```
+
+WIP
