feat(docs): add readme

Author: not-matthias

README.md

@@ -1 +1,50 @@
-# codspeed-go
+<div align="center">
+<h1>codspeed-go</h1>
+
+[![CI](https://github.com/CodSpeedHQ/codspeed-go/actions/workflows/ci.yml/badge.svg?branch=main)](https://github.com/CodSpeedHQ/codspeed-go/actions/workflows/ci.yml)
+[![Discord](https://img.shields.io/badge/chat%20on-discord-7289da.svg)](https://discord.com/invite/MxpaCfKSqF)
+[![CodSpeed Badge](https://img.shields.io/endpoint?url=https://codspeed.io/badge.json)](https://codspeed.io/CodSpeedHQ/codspeed-go)
+
+</div>
+
+This repo contains the integration libraries for using CodSpeed in Go:
+
+- [`go-runner`](./go-runner/): Golang benchmark builder and runner
+- [`compat/testing`](./compat/testing/): Compatibility layer for the `testing` package.
+
+## Usage
+
+Integrating CodSpeed into your Go codebase requires **no modification**. You can continue using `go test` and the `testing` package as you normally would. When running your benchmarks in CI with CodSpeed, we will manually build and run the benchmarks and report the results to CodSpeed.
+
+For information on how to integrate it, see the [CodSpeed documentation](https://codspeed.io/docs/benchmarks/golang). If you need further information to integrate CodSpeed to your project, please feel free to open an issue or ask for help on our discord server.
+
+
+## Manual Usage
+
+To run the benchmarks with CodSpeed locally, you need to install the `go-runner` crate which is used to build and execute the benchmarks with instrumentation:
+```bash
+$ cd go-runner
+$ cargo install --path .
+```
+
+Then you can run the benchmarks with (the syntax is equivalent to `go test` but supports fewer flags). This will print all the benchmarks that can be run with CodSpeed and warnings if some benchmarks are not supported.
+```bash
+$ cd example
+$ export CODSPEED_PROFILE_FOLDER=/tmp/codspeed
+$ go-runner test -bench=.
+[INFO  go_runner] Discovered 1 package
+[INFO  go_runner] Total benchmarks discovered: 2
+[INFO  go_runner] Found BenchmarkFibonacci10           in "fib_test.go"
+[INFO  go_runner] Found BenchmarkFibonacci20_Loop      in "fib_test.go"
+[INFO  go_runner] Generating custom runner for package: example
+[INFO  go_runner] Running benchmarks for package: example
+Running with CodSpeed instrumentation
+goos: linux
+goarch: amd64
+cpu: 12th Gen Intel(R) Core(TM) i7-1260P @ 1672.130MHz
+BenchmarkFibonacci10/fibonacci(10)/fibonacci(10)-16                    1              1523 ns/op
+BenchmarkFibonacci20_Loop-16                                           1             31373 ns/op
+PASS
+[INFO  go_runner] Parsed 2 raw results
+[INFO  go_runner] Results written to "/tmp/codspeed/results/177951.json"
+```