Add concrete "hello world" example to App Developer getting started guide

[adambkaplan]

Which area this feature is related to?

/area documentation

Which area is this documentation change is related to?

/area landing-page

Issue details

The "Getting Started" guide for application developers does not contain any concrete examples on how to incorporate a devfile into your source code, nor does it provide guidance on how to choose the right one for you.

After reading the getting started page, I should be able to add a devfile to my source code repository and use it with a tool that supports devfiles (ex - odo).

Page: https://devfile.io/docs/2.2.0/application-developer

Target Date: 05-30-2023

[michael-valdron]

Thank you for your feedback @adambkaplan, one of our goals for Q2 2023 is to provide improvements to our doc pages with the new user in mind. I have opened an epic issue to track any other issues towards this goal: #1080

For this issue, we will specifically address the main subject of creating a straightforward "Hello world" example guide for getting started with devfiles which will also make reference to the relevant material for two devfile supporting developer tools odo and Eclipse Che so that a new user can try out their first devfile for themselves.

As for the Application Developer page, I have opened another issue which will address this piece: #1079

[elsony]

Additional requirement:
This "hello world" guide will need to be referenced by:

1. the page https://devfile.io/docs/2.2.0/developing-with-devfiles as a natural progression for developing devfile after the Intro section
2. the pages https://devfile.io/docs/2.2.0/application-developer and https://devfile.io/docs/2.2.0/enterprise-architect-and-runtime-provider as those are tasks that are likely to be done by those personas.

[michael-valdron]

Due to the backlog of items in this past sprint, this issue will be targeted for the upcoming sprint.

[michael-valdron]

Creating an instruction on setting up a simple devfile for using the expressjs hello world example application with odo v3. This instruction will go step by step on adding the fields needed to make this work to help a new adopter learn what each piece does. This generally flows the following way:

1. Create application source files
2. Create the devfile
3. Step by step construction of the devfile
4. How to run with odo
5. A extra piece to briefly show that odo init could be used instead to quickstart with the nodejs stack from the devfile registry

Also looking into an upcoming mirrored instruction with Eclipse Che.

[michael-valdron]

A draft for the hello world example with odo guide is contained in devfile/devfile-web#87. The Eclipse Che version of this guide will need additional time for completion due to set backs experienced in other issues I am working on. Therefore, the upcoming sprint will become the new target.

[michael-valdron]

Final drafts of the hello world starter guides for odo version 3 and Eclipse Che are now ready for review: devfile/devfile-web#87

[michael-valdron]

Final drafts of the hello world starter guides for odo version 3 and Eclipse Che are now ready for review: devfile/devfile-web#87

Adjusted target date for this issue to give the review process more time. Reaching out to members of odo and Eclipse Che to provide reviews on the respective guides.