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

@@ -91,7 +91,7 @@ These two files are executable `detect` and `build` scripts. You are now able to
 
 ### Using your buildpack with `pack`
 
-In order to test your buildpack, you will need to run the buildpack against your sample Ruby app using the `pack` CLI.
+In order to test your buildpack, you will need to run the buildpack against your sample Node.js app using the `pack` CLI.
 
 Set your default [builder][builder] by running the following:
 
@@ -137,4 +137,4 @@ ERROR: failed to detect: buildpack(s) failed with err
 <a href="/docs/buildpack-author-guide/create-buildpack/detection" class="button bg-pink">Next Step</a>
 
 [builder]: /docs/concepts/components/builder
-<!--+ end +-->
+<!--+ end +-->