Update guides to take advantage of existing codestarts

[ia3andy]

Description

Those guides present extensions which already have a codestart and which could be adapted to use it:

• https://quarkus.io/guides/picocli
• https://quarkus.io/guides/rest-json
• https://quarkus.io/guides/funqy-http
• https://quarkus.io/guides/resteasy-qute

cc @maxandersen

[ghost]

/cc @geoand, @matejvasek, @patriot1burke, @quarkusio/devtools

[gsmet]

We need to be extremely careful about this: the guide still needs to be explanatory and to contain the important information for the user.

Having the project all created by codestarts won't help to understand what's going on.

[ia3andy]

We need to be extremely careful about this: the guide still needs to be explanatory and to contain the important information for the user.

Having the project all created by codestarts won't help to understand what's going on.

Yes I agree, as a guideline for our guide, we could advise to use -noExamples to do the tuto and remove it (or see the quickstart) to directly have the solution.

[ia3andy]

In 2.0 codestarts are the beginning of guides, so we can now consider using them.

[patriot1burke]

Yeah, the codestarts are too simple and almost not useful enough for even hello world.