add FAQ, non-default packages (#1708)

## Summary

Adds an FAQ, and details about non-default packages via Flake Refrences

## How was it tested?

Build + preview locally

---------

Signed-off-by: John Lago <[email protected]>
Co-authored-by: Lucille Hua <[email protected]>

Author: Lagoja

docs/app/devbox.json

@@ -4,7 +4,4 @@
     "nodejs": "latest"
   },
   "shell": {},
-  "nixpkgs": {
-    "commit": "f80ac848e3d6f0c12c52758c0f25c10c97ca3b62"
-  }
 }

docs/app/docs/faq.md

@@ -0,0 +1,54 @@
+---
+title: Frequently Asked Questions
+description: Frequently Asked Questions about Devbox
+---
+
+This doc contains answers to frequently asked questions about Devbox that are not covered elsewhere in our documentation. If you have a question that isn't covered here, feel free to ask us on our [Discord](https://discord.gg/jetpack-io), or [open an issue](https://github.com/jetpack-io/devbox/issues) on our GitHub repository.
+
+## How does Devbox work?
+
+Devbox generates isolated, reproducible development environments using the [Nix package manager](https://nixos.org/). Devbox uses Nix to install packages, and then creates an isolated shell environment for your project by symlinking the packages you need into your project directory.
+
+## Where does Devbox install my packages?
+
+Devbox and Nix install your packages in the read-only Nix store, usually located at `/nix/store`. Devbox then creates your environment by symlinking the packages you need into the `.devbox` directory in your project.
+
+## How do I clean up unused packages from the Nix Store?
+
+You can use `devbox run -- nix store gc` to automatically clean up packages that are no longer needed for your projects.
+
+## Does Devbox require Docker or Containers to work?
+
+No. Since Devbox uses Nix to install packages and create isolated environments, Docker is not required. If you want to run your Devbox project inside a container, you can generate a Dockerfile or devcontainer.json using the `devbox generate` command.
+
+## What versions of Nix are supported by Devbox?
+
+Devbox requires Nix >= 2.12. If Nix is not present on your machine when you first run Devbox, it will automatically try to install the latest supported version for you.
+
+## Can I use Devbox with NixOS?
+
+Yes! Devbox can be installed on any Linux distribution, including NixOS. You can even install Devbox via Nixpkgs. See the [installation guide](./installing_devbox.mdx) for more details.
+
+## A package I installed is missing header files or libraries I need for development. Where do I find them?
+
+In order to save space, Devbox and Nix only install the required components of packages by default. Development header files and libraries are often installed in a separate output of the package (usually `dev`), which can be installed using [Flake References](./guides/using_flakes.md).
+
+You can learn more about non-default outputs [here](./guides/using_flakes.md#installing-additional-outputs-from-a-flake).
+
+## How can I use custom Nix packages or overrides with Devbox?
+
+You can add customized packages to your Devbox environment using our [Flake support](./guides/using_flakes.md). You can use these flakes to modify or override packages from nixpkgs, or to create your own custom packages.
+
+## Can I use Devbox if I use [Fish](https://fishshell.com/)?
+
+Yes. In addition to supporting POSIX compliant shells like Zsh and Bash, Devbox also works with Fish.
+
+## How can I uninstall Devbox?
+
+To uninstall Devbox:
+
+1. Remove the Devbox launcher using `rm /usr/local/bin/devbox`
+2. Remove the Devbox binaries using `rm -rf ~/.cache/devbox`
+3. Remove your Devbox global config using `rm -rf .local/share/devbox`
+
+If you want to uninstall Nix, you will need to follow the instructions in the Nix Documentation: https://nixos.org/manual/nix/stable/installation/uninstall.

docs/app/docs/guides/using_flakes.md

@@ -65,6 +65,16 @@ For example, if you want to install the `hello` package from the `nixos-20.09` b
 github:NixOS/nixpkgs/nixos-20.09#hello
 ```
 
+## Installing Additional Outputs from a Flake
+
+Some packages provide additional outputs that are not installed by default. For example, the `libcap` package provides a `dev` output that contains development headers and libraries, or the `prometheus` package includes the `promtool` CLI in a `cli` output.
+
+You can install these additional outputs by adding a `^` and a comma-separated list of outputs to the end of your flake reference. For example, the following command will install the default (`out`) and `dev` outputs of the `libcap` package:
+
+```nix
+github:nixos/nixpkgs#libcap^out,dev
+```
+
 ## Using a Local Flake
 
 You can also use a local Flake using the `path` attribute in your package list. Using a local flake can be helpful if you want to install your custom packages with Nix, or if you need to modify packages before using them in your Devbox project

docs/app/sidebars.js

@@ -142,6 +142,9 @@ const sidebars = {
                 dirName: 'devbox_examples/stacks'
             }]
         }]
+    }, {
+        type: 'doc',
+        id: 'faq'
     }],
 };