Document how to upgrade projects to Cookieplone

[stevepiercy]

Although we tell developers to upgrade their projects to Cookieplone, we don't explicitly say how to do so. Without these docs, developers may be reluctant to try upgrading to Volto 18, because they don't know where to move things from the previous structure to the new one.

Originally posted by @stevepiercy in #6541 (comment)

[davisagli]

@stevepiercy that notice says how at a high level: "when you want to upgrade your project, you can generate a new project using Cookieplone with the same name as your old one, and copy over your add-ons to the new project." Sounds like you're looking for a more detailed guide to doing that in a separate chapter?

[stevepiercy]

@davisagli see your comment in the original issue.

[davisagli]

@stevepiercy The update to this notice which happened in #6609 is exactly what I had in mind when I wrote that comment.

[stevepiercy]

@davisagli I don't know if it needs more detail, such as copy from this folder to that folder. If you think it's good enough, then you can close this issue.

[davisagli]

@stevepiercy I'm not the right person to evaluate that, since I haven't done any of these upgrades recently.

[stevepiercy]

@davisagli me neither. ☹ @plone/volto-team have any of you done such an upgrade recently who can provide notes or an outline? I'd be happy to do the necessary write up, I just don't know the necessary details.

[erral]

I have upgraded some add-ons that way. Perhaps we can improve the text with some more details like saying which folder you should copy to which folder in the new structure

[stevepiercy]

@erral yes, please! If you can provide details, even mere notes, I would be grateful and write up docs from them.

[erral]

Here you have some quick notes:

• Create the project structure with cookieplone using the frontend_addon template
• Take the contents of the src folder in the old structure, and copy them over to packages/<your-addon-name>/src/

Here you have some examples of such an update:

• update for Volto 18 codesyntax/volto-maplibre-block#4
• update for volto 18 codesyntax/volto-countup-block#5