Remove unwanted files and folders from doc folder

Author: dhoomakethu

.gitignore

@@ -28,3 +28,5 @@ test/__pycache__/
 /doc/quality/
 /doc/pymodbus.pdf
 /doc/sphinx/
+/doc/html/
+/doc/_build/

Makefile

@@ -46,8 +46,8 @@ tox: install
 	@pip install --quiet tox && tox
 
 docs: install
-	@pip install --quiet sphinx
-	@cd doc/sphinx && sphinx-build -nb html -d doctrees . html
+	@pip install --quiet sphinx sphinx_rtd_theme
+	@cd doc && sphinx-build -nb html -d _build/doctrees . html
 
 publish: install
 	git push origin && git push --tags origin