Updated api.specification.md to adhere to gatsby style guide (#18311)

* Updated api.specification.md

* resolve some type

* enhancement some sentence

* Update docs/docs/api-specification.md

Co-Authored-By: Marcy Sutton <marcy@gatsbyjs.com>

docs/docs/api-specification.md

@@ -100,7 +100,7 @@ load site config -> load plugins -> source nodes -> transform nodes -> create
 graphql schema -> create pages -> compile component queries -> run queries ->
 fin
 
-Once the initial bootstrap is finished, we start `webpack-dev-server` and an express server for serving files for the development server, and for a production build, we start building the CSS then JavaScript then HTML with webpack.
+Once the initial bootstrap is finished, a `webpack-dev-server` and express server are started for serving files for the development workflow with live updates. For a production build, Gatsby skips the development server and instead builds the CSS, then JavaScript, then static HTML with webpack.
 
 During these processes there are various extension points where plugins can
 intervene. All major processes have an `onPre` and `onPost` e.g. `onPreBootstrap`