Merge Dockerfile and example files for backend support example (#7)

* Add template dockerfile for testing

* Switch to holo-docker image

* Add default entrypoint.sh

* Updated dockerfile to reflect CI/CD on database

* Add template makefile, main.c

* Adjusted entrypoint.sh to actually build binary

* Made entrypoint.sh executable

* Big README update and comments in Dockerfile

backend/Makefile

@@ -0,0 +1,14 @@
+# This is the default target, which will be built when 
+# you invoke make
+.PHONY: all
+all: hello
+
+# This rule tells make how to build hello from hello.cpp
+hello:
+	mkdir -p ./out
+	gcc -o ./out/hello ./src/main.c 
+
+# This rule tells make to delete hello and hello.o
+.PHONY: clean 
+clean:
+	rm -f hello