Add Dockerfile

Dockerfile

@@ -0,0 +1,11 @@
+FROM ubuntu:18.04
+
+RUN apt-get -y update && \
+    apt-get -y install g++ \
+                       gcc \
+                       git \
+                       make \
+                       zip
+COPY . /bannertool
+WORKDIR /bannertool
+CMD ["make"]

README.md

@@ -1,3 +1,11 @@
 # bannertool
 
 A tool for creating 3DS banners.
+
+## How to build (Using Docker)
+
+```bash
+docker build -t bannertool-builder .
+docker run --name bannertool-builder bannertool-builder
+docker cp bannertool-builder:/bannertool/output/bannertool.zip .
+```