Add missing period

Author: mattfbacon

Dockerfile

@@ -21,7 +21,7 @@ CMD [ "/bot/typst-bot" ]
 ENV DB_PATH=/bot/sqlite/db.sqlite \
     CACHE_DIRECTORY=/bot/cache
 
-# Create the necessary directories and the empty database file
+# Create the necessary directories and the empty database file.
 RUN mkdir -p /bot/sqlite /bot/cache && \
     touch /bot/sqlite/db.sqlite