Updated Linux instructions (markdown)

Linux-instructions.md

@@ -1,7 +1,7 @@
 With most desktop-oriented distributions, double-clicking the font file should be enough. If it isn’t (e.g., xubuntu), try this:
 
-1. `mkdir ~/.local/share/fonts`
-2. Put font files in that directory.
-3. `fc-cache -f`
+1. `mkdir -p ~/.local/share/fonts`
+1. `for type in Bold Light Medium Regular Retina; do wget -O ~/.local/share/fonts/FireCode-$type.ttf https://github.com/tonsky/FiraCode/blob/master/distr/ttf/FiraCode-$type.ttf?raw=true; done`
+1. `fc-cache -f`
 
 [More details](https://github.com/tonsky/FiraCode/issues/4)