feat: add install guide

INSTALL.md

@@ -0,0 +1,35 @@
+# Installing VPKEdit
+
+This document covers the different ways you can install VPKEdit on its supported
+platforms:
+
+- Windows 10/11 (64-bit)
+- Linux (64-bit)
+
+Note: if you wish to *update* the application, simply repeat these steps. This works for
+both the standalone method and installer method.
+
+## Windows
+
+1. You will need to install the VS2015-2022 runtime located at https://aka.ms/vs/16/release/vc_redist.x64.exe.
+2. When that is installed, download either the standalone version or the installer version from [the latest
+   GitHub release](https://github.com/craftablescience/VPKEdit/releases/latest), under the `Assets` dropdown.
+3. If you downloaded the standalone files, you're done, just unzip the files. If you downloaded the installer,
+   unzip the installer application and run it. Windows will give you a safety warning, ignore it and hit `Run Anyway`.
+
+## Linux
+
+Installation on Linux will vary depending on your distro. On all distros you should be able to run the standalone
+application without any issues. There are two ways of *installing* VPKEdit
+specific to the following distros:
+
+#### Debian-based:
+
+1. Download the installer from the GitHub releases section, and extract the `.deb` file from inside.
+2. Run `sudo apt install ./<name of deb file>.deb` in the directory you extracted it to.
+
+#### Arch-based:
+
+VPKEdit is on the Arch User Repository thanks to [@HurricanePootis](https://github.com/HurricanePootis).
+Please consult the [Arch Wiki](https://wiki.archlinux.org/title/Arch_User_Repository) for more information,
+as I don't use Arch Linux personally and don't know how that system works. (I use Debian btw)

README.md

@@ -7,6 +7,10 @@ VPKEdit is an open source MIT-licensed tool that can create, extract from, previ
 
 <img src="https://github.com/craftablescience/VPKEdit/blob/main/branding/readme_promo.png?raw=true" alt="A screenshot of VPKEdit with a VTF preview open." />
 
+## Installing
+
+Please read [this file](https://github.com/craftablescience/VPKEdit/blob/main/INSTALL.md) for step-by-step installation instructions.
+
 ## Features
 
 - Create VPKs of any version from scratch or an existing folder