chore: add minimal README including codecov and build

commit-id:841310c2

README.md

@@ -1 +1,17 @@
-# mempool
+<div align="center">
+  <h1>Mempool</h1>
+  <br />
+  <a href="https://github.com/starkware-libs/mempool/issues/new?assignees=&labels=bug&template=01_BUG_REPORT.md&title=bug%3A+">Report a Bug</a>
+  ·
+  <a href="https://github.com/starkware-libs/mempool/issues/new?assignees=&labels=enhancement&template=02_FEATURE_REQUEST.md&title=feat%3A+">Request a Feature</a>
+  ·
+  <a href="https://github.com/starkware-libs/mempool/discussions/new?category=q-a">Ask a Question</a>
+</div>
+
+<div align="center">
+<br />
+
+[![GitHub Workflow Status](https://github.com/starkware-libs/mempool/actions/workflows/post-merge.yml/badge.svg)](https://github.com/starkware-libs/mempool/actions/workflows/post-merge.yml)
+[![codecov](https://codecov.io/gh/starkware-libs/mempool/branch/main/graph/badge.svg?token=Z5MXY45MR5)](https://codecov.io/gh/starkware-libs/mempool)
+
+</div>