Update README with Ubuntu compiling notes

README

@@ -1,4 +1,3 @@
-
   0. Usage
 ============
 
@@ -59,6 +58,9 @@ As for dependencies, diff-pdf requires the following libraries:
   * sudo yum groupinstall "Development Tools"
   * sudo yum install wxGTK wxGTK-devel poppler-glib poppler-glib-devel
 
+ Ubuntu:
+  * sudo apt-get install libpoppler-glib-dev poppler-utils wxgtk2.8-dev automake
+
 Note that many more libraries are required on Windows, where none of the
 libraries Cairo and Poppler use are normally available. At the time of writing,
 transitive cover of the above dependencies included fontconfig, freetype, glib,