add snippet folder to docker build

Dockerfile

@@ -11,6 +11,7 @@ RUN cargo build --release
 COPY --chown=rust src ./src
 COPY --chown=rust static ./static
 COPY --chown=rust template ./template
+COPY --chown=rust snippet ./snippet
 COPY --chown=rust init-db.sql ./init-db.sql
 RUN touch src/main.rs
 RUN cargo build --release