Merge pull request #3 from mozilla/feat-readme

feat: Add a README

README.md

@@ -0,0 +1,27 @@
+# MTU
+
+A crate to return the maximum transmission unit (MTU) of the local network interface towards a given destination `SocketAddr`.
+
+## Usage
+
+This crate exports a single function
+
+```rust
+pub fn get_interface_mtu(remote: &SocketAddr) -> Result<usize, Error>
+```
+
+that returns the MTU of the local network interface towards the `remote` destination, or an `Error` when the MTU could not be determined. It supports both IPv4 and IPv6.
+
+## Supported Platforms
+
+* Linux
+* macOS
+* Windows
+
+## Notes
+
+The returned MTU may exceed the maximum IP packet size of 65,535 bytes on some platforms for some remote destinations. (For example, loopback destinations on Windows.)
+
+## Contributing
+
+We're happy to receive PRs that improve this crate. Please take a look at our [community guidelines](CODE_OF_CONDUCT.md) beforehand.