README: add missing badges

Including Coverage badge, a part of #429.

Signed-off-by: Anna Shaleva <[email protected]>

README.md

@@ -7,6 +7,12 @@
 
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+[![codecov](https://codecov.io/gh/nspcc-dev/neo-go/branch/master/graph/badge.svg)](https://codecov.io/gh/nspcc-dev/neofs-contract)
+[![GithubWorkflows Tests](https://github.com/nspcc-dev/neofs-contract/actions/workflows/go.yml/badge.svg)](https://github.com/nspcc-dev/neofs-contract/actions/workflows/go.yml)
+[![Report](https://goreportcard.com/badge/github.com/nspcc-dev/neofs-contract)](https://goreportcard.com/report/github.com/nspcc-dev/neofs-contract)
+![GitHub release (latest SemVer)](https://img.shields.io/github/v/release/nspcc-dev/neofs-contract?sort=semver)
+![License](https://img.shields.io/github/license/nspcc-dev/neofs-contract.svg?style=popout)
+
 # Overview
 
 NeoFS-Contract contains all NeoFS related contracts written for