Remove cache - first draft

sections/docker/clean-cache.md

@@ -0,0 +1,25 @@
+# Clean NODE_MODULE cache
+
+<br/><br/>
+
+### One Paragraph Explainer
+
+Node package managers, npm & Yarn, cache the installed packages locally so that future projects which need the same libraries won't need to fetch from a remote repository. Although this duplicates the packages and consumes more storage - it pays off in a local development environment that typically keeps installing the same packages. In a Docker container, this storage increase is worthless since it installs the dependency only once. By removing this cache, using a single line of code, tens of MB are shaved from the image. While doing so, ensure that it doesn't exit with non-zero code and fail the CI build because of caching issues - This can be avoided by including the --force flag
+
+<br/><br/>
+
+### Code Example – Clean cache
+
+<details>
+<summary><strong>Dockerfile</strong></summary>
+
+```
+FROM node:12-slim AS build
+WORKDIR /usr/src/app
+COPY package.json package-lock.json ./
+RUN npm ci --production && npm clean cache --force
+
+# The rest comes here
+```
+
+</details>