Getting Started > Fundamentals of Block Development: Clarify requirements to add editor styles for a block

[juanmaguitar]

As per this conversation in the #outreach channel at Make WordPress Slack and the following feedback provided by @luminuu

But maybe the tutorial should be updated/enhanced to reflect these kind of things:

• The editor.css file has to be called from the index.js or the edit.js, if that's an extra file with import /.editor.css
• In the block.json, the editorStyle needs to refer to the index.css file, because that's the one that is generated in the build folder
  I guess I won't be the only one who will struggle with this.

The Getting Started section needs to be reviewed to ensure that the feedback above is addressed and that the requirements for adding editor styles for a block are clear. Also evaluate id such explanations belong to #56275 and plan proper connections/links from current subpages (File structure of a block or block.json for example) if that's the best course of action

cc: @ndiego