Added '.dockgerignore' file to repo so that only essential files and folders are copied when building Docker image

Author: tieneupin

.dockerignore

@@ -0,0 +1,11 @@
+# Ignore everything by default
+**
+
+# Whitelist only the files and folders needed for building
+!Dockerfiles/
+!src/
+!pyproject.toml
+!setup.py
+!LICENSE
+!MANIFEST.in
+!README.md