chore(docs): Update the "Gatsby on Linux" page (#18263)

* remove "todo" stub, make links visible, add extra links

* Incorporate comments and update instructions for Linux

* respond to comments

* Apply suggestions from code review

Apply @marcysutton's suggestions

Co-Authored-By: Marcy Sutton <marcy@gatsbyjs.com>

* remove empty line, fix link at the bottom

- Removed an empty line that was probably making the tests fail
- Fixed a link from the additional links section

docs/docs/gatsby-on-linux.md

@@ -2,12 +2,124 @@
 title: Gatsby on Linux
 ---
 
-> This is a TODO. Help our community expand it.
+This guide assumes you already have a native installation of Linux on your machine. The following steps walk through how to install Node.js and associated dependencies.
 
-> Please use the [Gatsby Style Guide](/contributing/gatsby-style-guide/) to ensure your pull request gets accepted.
+## Ubuntu, Debian, and other `apt` based distros
+
+Begin by updating and upgrading.
+
+```shell
+sudo apt update
+sudo apt -y upgrade
+```
+
+Install curl which allows you to transfer data and download additional dependencies.
+
+```shell
+sudo apt install curl
+```
+
+Once `curl` is installed, you can use it to install `nvm`, which will manage `node` and all its associated versions.
+
+```shell
+curl -o- https://raw.githubusercontent.com/nvm-sh/nvm/v0.35.1/install.sh | bash
+```
+
+> Note that this is the current stable release of nvm. Full installation instructions and troubleshooting can be found at the [nvm GitHub page](https://github.com/nvm-sh/nvm)
+
+When `nvm` is installed, it does not default to a particular `node` version. You'll need to install the version you want and give `nvm` instructions to use it. This example uses the latest release of version `10`, but more recent version numbers can be used instead.
+
+```shell
+nvm install 10
+nvm use 10
+```
+
+To confirm this has worked, use the following command.
+
+```shell
+node -v
+```
+
+> Note that `npm` comes packaged with `node`
+
+Finally, install `git` which will be necessary for creating your first Gatsby project based on a starter.
+
+```shell
+sudo apt install git
+```
+
+## Fedora, RedHat, and other `dnf` based distros
+
+These distros come installed with `curl`, so you can use that to download `nvm`.
+
+```shell
+curl -o- https://raw.githubusercontent.com/nvm-sh/nvm/v0.35.1/install.sh | bash
+```
+
+> Note that this is the current stable release of nvm. Full installation instructions and troubleshooting can be found at the [nvm GitHub page](https://github.com/nvm-sh/nvm)
+
+When `nvm` is installed, it does not default to a particular `node` version. You'll need to install the version you want and give `nvm` instructions to use it. This example uses the latest release of version `10`, but more recent version numbers can be used instead.
+
+```shell
+nvm install 10
+nvm use 10
+```
+
+To confirm this has worked, use the following command.
+
+```shell
+node -v
+```
+
+> Note that `npm` comes packaged with `node`
+
+Finally, install `git` which will be necessary for creating your first Gatsby project based on a starter.
+
+```shell
+sudo dnf install git
+```
+
+## Archlinux and other `pacman` based distros
+
+Begin by updating.
+
+```shell
+sudo pacman -Sy
+```
+
+These distros come installed with `curl`, so you can use that to download `nvm`.
+
+```shell
+curl -o- https://raw.githubusercontent.com/nvm-sh/nvm/v0.35.1/install.sh | bash
+```
+
+> Note that this is the current stable release of nvm. Full installation instructions and troubleshooting can be found at the [nvm GitHub page](https://github.com/nvm-sh/nvm)
+
+Before using `nvm`, you need to install additional dependencies.
+
+```shell
+sudo pacman -S grep awk tar git
+```
+
+When `nvm` is installed, it does not default to a particular `node` version. You'll need to install the version you want and give `nvm` instructions to use it. This example uses the latest release of version `10`, but more recent version numbers can be used instead.
+
+```shell
+nvm install 10
+nvm use 10
+```
+
+To confirm this has worked, use the following command.
+
+```shell
+node -v
+```
+
+> Note that `npm` comes packaged with `node`
 
 ## Windows Subsystem Linux (WSL)
 
+This guide assumes that you already have WSL installed with a working Linux distro. If you don't, follow [this guide from Microsoft's site](https://docs.microsoft.com/en-us/windows/wsl/install-win10) to install WSL and a Linux distro of your choice.
+
 As of October 17th 2017, Windows 10 ships with WSL and Linux distributions are available via the [Windows Store], there are several different distributions to use which can be configured via `wslconfig` if you have more than one distribution installed.
 
 ```shell
@@ -24,8 +136,6 @@ sudo apt update
 sudo apt -y upgrade
 ```
 
-> Only use `-y` if you're happy to upgrade to the latest versions of the software.
-
 **Build tools**
 
 To compile and install native addons from npm you may also need to install build tools for `node-gyp`:
@@ -48,9 +158,16 @@ There are other alternatives for managing your node versions such as [nvm] but t
 
 Debian setup is nearly identical to Ubuntu except for the additional installs of `git` and `libpng-dev`.
 
+Begin by updating and upgrading.
+
 ```shell
 sudo apt update
 sudo apt -y upgrade
+```
+
+Additional dependencies need to be installed as well. `build-essential` is a package that allows other packages to compile to a Debian package. `git` installs a package to work with version control. `linbpng-dev` installs a package that allows the project to manipulate images.
+
+```shell
 sudo apt install build-essential
 sudo apt install git
 sudo apt install libpng-dev
@@ -62,10 +179,11 @@ Or to install all at the same time and approve `(y)` all installs:
 sudo apt update && sudo apt -y upgrade && sudo apt install build-essential && sudo apt install git && sudo apt install libpng-dev
 ```
 
-<!-- links -->
+### Additional links and resources
 
-[windows store]: https://www.microsoft.com/en-us/store/p/ubuntu/9nblggh4msv6
-[n]: https://github.com/tj/n
-[n-install]: https://github.com/mklement0/n-install
-[nvm]: https://github.com/creationix/nvm
-[bash startup]: https://github.com/Microsoft/WSL/issues/776#issuecomment-266112578
+- [Super detailed guide to making VSCode work with ESL from VSCode's docs website](https://code.visualstudio.com/docs/remote/wsl)
+- [Windows store page for downloading Ubuntu on Windows](https://www.microsoft.com/en-us/store/p/ubuntu/9nblggh4msv6)
+- [n](https://github.com/tj/n)
+- [nvm](https://github.com/creationix/nvm)
+- [n-install](https://github.com/mklement0/n-install)
+- [bash startup](https://github.com/Microsoft/WSL/issues/776#issuecomment-266112578)