add README with build instructions

README.md

@@ -0,0 +1,23 @@
+# File Manager
+
+File Manager is a simple file manager made using Raven.
+
+# Dependencies
+
+ - [raven](https://git.hippoz.xyz/hippoz/raven)
+ - librsvg
+
+# Hacking
+
+```
+$ meson builddir
+$ cd builddir
+$ meson compile
+```
+
+You should now have a `filemanager` binary in the build directory.
+
+You also need to download the folder icon SVG. You can use the Papirus one (license: GNU General Public License v3.0):
+```
+wget https://raw.githubusercontent.com/PapirusDevelopmentTeam/papirus-icon-theme/master/Papirus/64x64/places/folder-adwaita.svg
+```