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+# Overview
+
+GRM is still in very early development. I started GRM mainly to scratch my own
+itches (and am heavily dogfooding it). If you have a new use case for GRM, go
+for it!
+
+## Contributing
+
+To contribute, just fork the repo and create a pull request against `develop`.
+If you plan bigger changes, please consider opening an issue first, so we can
+discuss it.
+
+If you want, add yourself to the `CONTRIBUTORS` file in your pull request.
+
+## Branching strategy
+
+The branching strategy is a simplified
+[git-flow](https://nvie.com/posts/a-successful-git-branching-model/).
+
+* `master` is the "production" branch. Each commit is a new release.
+* `develop` is the branch where new stuff is coming in.
+* feature branches branch off of `develop` and merge back into it.
+
+Feature branches are not required, there are also changes happening directly on
+`develop`.
+
+## Required tooling
+
+You will need the following tools:
+
+* Rust (obviously) (easiest via `rustup`), with the nightly toolchain
+* Python3
+* [`just`](https://github.com/casey/just), a command runner like `make`. See
+  [here](https://github.com/casey/just#installation) for installation
+  instructions (it's most likely just a simple `cargo install just`).
+* Docker & docker-compose for the e2e tests
+* `black` and `shfmt` for formatting.
+* `shellcheck` for shell script linting
+* `mdbook` for the documentation
+
+Here are the tools:
+
+| Distribution  | Command                                                                                             |
+| ------------- | --------------------------------------------------------------------------------------------------- |
+| Arch Linux    | `pacman -S --needed python3 rustup just docker docker-compose python-black shfmt shellcheck mdbook` |
+| Ubuntu/Debian | `apt-get install --no-install-recommends python3 docker.io docker-compose black shellcheck`         |
+
+Note that you will have to install `just` and `mdbook` manually on Ubuntu (e.g.
+via `cargo install just mdbook` if your rust build environment is set up
+correctly). Same for `shfmt`, which may just be a `go install
+mvdan.cc/sh/v3/cmd/shfmt@latest`, depending on your go build environment.
+
+For details about rustup and the toolchains, see [the installation
+section](./installation.md).
+
+## FAQ
+
+### Why nightly?
+
+For now, GRM requires the nightly toolchain for two reasons:
+
+* [`io_error_more`](https://github.com/rust-lang/rust/issues/86442) to get
+  better error messages on IO errors
+* [`const_option_ext`](https://github.com/rust-lang/rust/issues/91930) to have
+  static variables read from the environment that fall back to hard coded
+  defaults
+
+Honestly, both of those are not really necessary or can be handled without
+nightly. It's just that I'm using nightly anyway.