Add docs generation to rakefile

Author: vallode

.luarc.json

@@ -11,6 +11,11 @@ task :build do
   ruby 'lib/generate.rb'
 end
 
+task :docs do
+  sh 'lua-language-server --configpath=.luarc.json --doc_out_path=docs  --doc=dist/library'
+  ruby 'lib/json.rb'
+end
+
 task :debug do
   ruby 'lib/generate.rb --debug'
 end