Bump to 2.0.0, Added nil return, added rockspec (#2)

* Added rockspec file
* Added rock build action
* Added explicit `nil` return
* Bumped to v2.0.0

.github/workflows/packaging.yml

@@ -25,7 +25,7 @@ jobs:
 
       - name: Preparing build directory
         run: |
-          mkdir -p build/lua/doc
+          mkdir -p build/lua/doc/../lua
 
       - name: Build LDoc documentation
         uses: lunarmodules/ldoc@v1.5.0
@@ -38,6 +38,7 @@ jobs:
           cp LICENSE build/LICENSE
           cp demo.lua build/demo.lua
           cp -R doc/ build/doc/
+          cp -R lua/ build/lua/
           cp LICENSE build/doc/topics/LICENSE
 
       - name: Upload artifact (socket.7z)