Add install documentation

INSTALL.md

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+For Windows, you can download the latest prebuilt release [here](https://github.com/stacksmashing/openocd-tamarin/releases/tag/latest).
+
+For macOS, we prepared a custom homebrew tap, and so if you have Homebrew installed you can just run:
+
+```
+brew tap stacksmashing/homebrew-tap
+brew install --HEAD stacksmashing/tap/openocd-tamarin
+```
+
+If you need to update the openocd version, run:
+
+```
+brew upgrade stacksmashing/tap/openocd-tamarin --fetch-HEAD
+```
+
+For Linux, you most probably need to build OpenOCD from source, our Github repository with Faultier compatibility can be found [here](https://github.com/stacksmashing/openocd-tamarin)!
+
+On Linux you will also need a udev rule so that your user can access Faultier. For example:
+
+```
+SUBSYSTEM=="usb", ATTR{idVendor}=="2B3E", ATTR{idProduct}=="2343", MODE="0666" 
+```
+in /etc/udev/rules.d/99-faultier.conf. Reboot after adding this line to make sure the changes take effect. Note that this will grant any user on the system access to Faultier.
+