Update Dockerfile

Dockerfile

@@ -6,6 +6,10 @@ RUN corepack enable
 WORKDIR /usr/src/app
 
 COPY . .
+# Use the --immutable flag as a precaution. This guarantees that the Docker
+# build will fail if `yarn install` results in a different yarn.lock file than
+# the one checked into the repo. This could happen for example if the version of
+# Yarn used in one dev environment differs from the version used here.
 RUN --mount=type=cache,target=/root/.yarn YARN_CACHE_FOLDER=/root/.yarn \
     yarn install --immutable --network-timeout 600000 && \
     if [[ ! -f ".env" ]]; then mv .env.example .env; fi;