Added option to configure china's internal mirrors.

Dockerfile

@@ -47,6 +47,10 @@ RUN mkdir -p /var/run/sshd
 # Allow non-root users to run sudo command without password
 RUN echo "ALL ALL=NOPASSWD:ALL" > /etc/sudoers.d/01-allow-sudo
 
+# Set system-wide git configs
+RUN git config --system user.name "ameer" && \
+    git config --system user.email "ameer@ahkhan.me"
+
 COPY scripts/entrypoint.sh /entrypoint.sh
 RUN chmod +x /entrypoint.sh