Update Readme.md

Readme.md

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 [![Crates](https://badgen.net/crates/v/flex-dns)](https://crates.io/crates/flex-dns)
 [![License: MIT](https://img.shields.io/badge/License-MIT-yellow.svg)](https://opensource.org/licenses/MIT)
 [![CI](https://github.com/28Smiles/flex-dns/actions/workflows/rust.yml/badge.svg)](https://github.com/28Smiles/flex-dns/actions/workflows/rust.yml)
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 Flex-Dns is a DNS parser and serializer written in Rust. It is designed to be used in embedded systems, 
 but can also be used in other projects. For usage in embedded systems, we completely avoid the usage of the