[docs] Important info missing from Javascript

[marxjohnson]

What is the URL of the page?

https://moodledev.io/docs/guides/javascript

What is the issue with this page?

As highlighted in this discussion, the Javascript development guide doesn't mention the very important step of running grunt to build your Javascript. This is mentioned separately on the Modules page, but a new developer following the examples on the Javascript guide won't know to look there too. In fact, there appears to be quite a bit of duplication between these pages, both explaining Moodle's Javascript module format and both giving different examples of how to write "your first module".

Are you able to provide a patch for this?

None