Added Gollum with a build file

gollum/Dockerfile

@@ -0,0 +1,8 @@
+FROM ruby
+RUN apt-get -y update && apt-get -y install libicu-dev cmake && rm -rf /var/lib/apt/lists/*
+RUN gem install github-linguist
+RUN gem install gollum
+RUN gem install org-ruby  # optional
+WORKDIR /wiki
+ENTRYPOINT ["gollum", "--port", "80"]
+EXPOSE 80

gollum/docker-compose.yml

@@ -0,0 +1,7 @@
+version: '3'
+services:
+  gollum:
+    build: .
+    ports:
+      - "8080:80"
+    restart: unless-stopped