ARM toolchain docs for other distros

.gitignore

@@ -4,4 +4,5 @@
 /template
 Cargo.lock
 book/
-target/
+target/
+/.idea

src/03-setup/linux.md

@@ -34,6 +34,21 @@ $ sudo pacman -S \
   openocd
 ```
 
+- Other distros
+
+For distros that don't have packages for [ARM's pre-built toolchain](https://developer.arm.com/open-source/gnu-toolchain/gnu-rm/downloads), download the "Linux 64-bit" file and put its `bin` directory on your path. Here's one way to do it:
+
+``` console
+$ mkdir -p ~/local && cd ~/local
+$ tar xjf /path/to/downloaded/file/gcc-arm-none-eabi-7-2017-q4-major-linux.tar.bz2.tbz
+```
+
+Then, use your editor of choice to append to your `PATH` in the appropriate shell init file (e.g. `~/.zshrc` or `~/.bashrc`):
+
+```
+PATH=$PATH:$HOME/local/gcc-arm-none-eabi-7-2017-q4-major/bin
+```
+
 ## Optional packages
 
 - Ubuntu / Debian