docs: Add README

.editorconfig

@@ -11,3 +11,6 @@ tab_width = 4
 
 [{gah,*.sh,*.bash,*.bats}]
 indent_style = tab
+
+[*.md]
+indent_size = 2

README.md

@@ -0,0 +1,51 @@
+![gah! logo](./_static/logo.svg)
+
+`gah` is an GitHub Releases app installer, that does not require sudo. It is a simple bash script that downloads the latest release of an app from GitHub and installs it in `~/.local/bin`. It is designed to be used with apps that are distributed as a single binary file.
+
+Features:
+
+- Downloads the latest or given release of an app from GitHub
+- Automatically selects matching binary for the current platform
+
+  - Supported OS: Linux and MacOS
+  - Supported architectures: x64 and ARM64
+
+- Supports multiple matching apps in a single GitHub Release
+- Supports archived (`.zip`, `.tar.gz`, `.tar.bz2`, `.tar.xz`) and single binary releases
+- Has own base of predefined aliases for GitHub repositories (PRs are welcome!)
+
+## Installation
+
+TODO
+
+## Usage
+
+Type `gah help` to see the list of available commands.
+
+```text
+gah
+  install <github_owner/github_repo_name | known_alias> [<git_tag>]
+  show <aliases>
+  help
+  version
+```
+
+## Examples
+
+### Install latest version of gh (GitHub CLI)
+
+```bash
+gah install gh
+```
+
+### Install specific version of argocd
+
+```bash
+gah install argocd v2.0.3
+```
+
+### Install an app that is not in the predefined aliases
+
+```bash
+gah install hashicorp/vagrant
+```