Using `echo` instead of `cat` is a bit complicated for beginners

[linghengqian]

Summary

• Using echo instead of cat is a bit complicated for beginners. See https://buildpacks.io/docs/for-buildpack-authors/tutorials/basic-buildpack/07_make-buildpack-configurable/ .
• I think the following snippet,

  
  plan=${CNB_BUILD_PLAN_PATH}
  version=3.1.3

if [[ -f .node-js-version ]]; then version=$(cat .node-js-version | tr -d '[:space:]') fi

echo "provides = [{ name = \"node-js\" }]" > "$plan" echo "requires = [{ name = \"node-js\", metadata = { version = \"$version\" } }]" >> "$plan"

- It should be changed to,
```shell
version=3.1.3

if [[ -f .node-js-version ]]; then
    version=$(< .node-js-version tr -d '[:space:]')
fi

cat > "${CNB_BUILD_PLAN_PATH}" << EOL
provides = [{ name = "node-js" }]
requires = [{ name = "node-js", metadata = { version = "$version" } }]
EOL

• This will avoid IntelliJ IDEA warnings.
• 

What questions should this documentation answer?

• Null.

Who is the target audience for this documentation?

• [ ] App Developer
• [x] Buildpack Author
• [ ] Operator
• [ ] Other:

Additional Information

• Originated from https://github.com/apache/shardingsphere/issues/32947 .

[linghengqian]

• I will submit a PR for this.