A blog post about extension development

[bajtos]

A blog post explaining to readers how easy it is to build an extension for LB Next, making people excited and wanting to write one!

Stakeholders to discuss the blog post with: @raymondfeng , @ritch, @kjdelisle, etc.

Promote @kjdelisle call for extensions: #509

See also #218

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Acceptance criteria

The blog post should be at relatively high level (think of extension-starter's README), for deeply technical content point readers to existing docs in other places.

• describe the scenario we have in mind (logger extension)
• why we have to build an extension using the structure we are going to follow (explain LoopBack-Next concepts)
• a step-by-step tutorial showing how to build this simple extension
• link to the repo with the completed example

Use @virkt25's example extension - a logger component providing a @log decorator, a sequence action and an app-level mixin to drive the post content.

[Setogit]

Combine with Raymond's blog series: https://github.com/strongloop/loopback-next/wiki/Crafting-LoopBack-Next In his words, "I’m starting to build this page to provide architectural insight and walkthrough for LB next"

Accompanied sample package: hello-extension is separated as task. #532

[bajtos]

Let's make this a short post bringing hello-extension into attention of people reading our blog. Keep most of the details in the actual hello-extension repository.