docs: add code for building docs in ci

docs/_build/Dockerfile

@@ -0,0 +1,12 @@
+FROM python:3.10-alpine
+
+WORKDIR /usr/src/app
+
+COPY docs/_build/requirements.txt .
+
+RUN apk add --no-cache bash yaml && \
+  pip install --no-cache-dir -r requirements.txt
+
+COPY docs/_build/entrypoint /bin/entrypoint
+
+ENTRYPOINT [ "/bin/entrypoint" ]