Update building-blocks-cnb.md

Update documentation: replace 'Ruby' with 'Node.js'

Changed the word 'Ruby' to 'Node.js' in the documentation to correct an inaccuracy with the previous content.

Signed-off-by: Ravindu Thiunuwan <[email protected]>

Author: thiunuwan

content/docs/buildpack-author-guide/create-buildpack/building-blocks-cnb.md

@@ -117,7 +117,7 @@ pack build test-node-js-app --path ./node-js-sample-app --buildpack ./node-js-bu
 ```
 <!--+- "{{execute}}"+-->
 
-The `pack build` command takes in your Ruby sample app as the `--path` argument and your buildpack as the `--buildpack` argument.
+The `pack build` command takes in your Node.js sample app as the `--path` argument and your buildpack as the `--buildpack` argument.
 
 After running the command, you should see that it failed to detect, as the `detect` script is currently written to simply error out.