add README.md with instructions on building

Author: umbynos

README.md

@@ -0,0 +1,29 @@
+# Arduino pluggable discovery for dfu devices
+
+The `dfu-discovery` tool is a command line program that interacts via stdio. It accepts commands as plain ASCII strings terminated with LF `\n` and sends response as JSON.
+
+## How to build:
+
+[Docker](https://www.docker.com/) is required to build this project, along with [task](https://taskfile.dev/).
+
+Just run `task download-dfu-util` to download dfu-util source code and then `task dist:<platform-to-build>`
+The platform to build can be one of:
+- Windows_32bit
+- Windows_64bit
+- Linux_32bit
+- Linux_64bit
+- Linux_ARMv6
+- Linux_ARMv7
+- Linux_ARM64
+- macOS_64bit
+- macOS_ARM64
+
+The executable `dfu-discovery` will be produced inside `dist/dfu-discovery-<platform>/dfu-discovery`.
+
+## Security
+
+If you think you found a vulnerability or other security-related bug in this project, please read our
+[security policy](https://github.com/arduino/mdns-discovery/security/policy) and report the bug to our Security Team 🛡️
+Thank you!
+
+e-mail contact: [email protected]