Add npm install step to docs instructions (#23385)

diff --git a/README.md b/README.md
index 96e26297b12e80893a6be5ff309b4a2c258eaad9..215d98b7c9c3138f845f581857677ecb89efae98 100644 (file)
--- a/README.md
+++ b/README.md
@@ -96,9 +96,10 @@ Documentation search is powered by [Algolia's DocSearch](https://community.algol
 ### Running documentation locally
 
 1. Run through the [tooling setup](https://github.com/twbs/bootstrap/blob/v4-dev/docs/4.0/getting-started/build-tools.md#tooling-setup) to install Jekyll (the site builder) and other Ruby dependencies with `bundle install`.
-2. Run `npm run test` (or a specific NPM script) to rebuild distributed CSS and JavaScript files, as well as our docs assets.
-3. From the root `/bootstrap` directory, run `bundle exec jekyll serve` in the command line.
-4. Open <http://localhost:9001> in your browser, and voilà.
+2. Run `npm install` to install Node.js dependencies.
+3. Run `npm run test` (or a specific NPM script) to rebuild distributed CSS and JavaScript files, as well as our docs assets.
+4. From the root `/bootstrap` directory, run `bundle exec jekyll serve` in the command line.
+5. Open <http://localhost:9001> in your browser, and voilà.
 
 Learn more about using Jekyll by reading its [documentation](https://jekyllrb.com/docs/home/).