[Docs] rake watch now rebuilds stylesheets independently from docs content so doc styling is faster

doc-src/Rakefile

@@ -24,10 +24,14 @@ task :watch do
   end
 
   rebuild_site = lambda do |base, relative|
-    if relative
-      puts ">>> Change Detected to #{relative} <<<"
+    if relative && relative =~ /\.s[ac]ss/
+      puts ">>> Change Detected to #{relative} : updating stylsheets <<<"
+      system "bundle exec compass compile"
     else
+      if !relative
         puts ">>> Compiling <<<"
+      else
+        puts ">>> Change Detected to #{relative} <<<"
       end
       start = Time.now
       # Nanoc3::CLI::Base.new.run(["co"])
@@ -43,6 +47,7 @@ task :watch do
         `growlnotify -m "Compilation Error!" --image misc/error-icon.png; exit 0`
       end
     end
+  end
   rebuild_site.call(nil,nil)
 
   puts ">>> Watching for Changes <<<"