[docs] Create documentation for implementing report builder support in plugins [Feature]

[NeillM]

What is the Moodle feature that needs documenting?

The report builder API documentation seems to talk about how it is implemented and some of the things that can be done with it, especially in regards to implementing system reports with it.

It is however entirely unclear to me from the documentation what a plugin would need to do to add support, for example what must be added to a plugin and where it must be placed in a minimum implementation.

As an example the attendance plugin extends a core_reportbuilder\datasource which is not mentioned in the documentation at all

Is this documentation specific to a Moodle version?

It is likely needed for all versions that support the report builder

Are you able to provide a patch for this?

None

[NeillM]

I'm currently working on improving them in: https://github.com/NeillM/devdocs/tree/reportbuilder

So far I have

• found that the 4.4 versions of the docs seem to not have been updated when some parts of the API were changed
• I have added a section about how to create a data source for custom reports
• Added some additional details about some of the things I have found out about them while implementing custom reports for one of our plugins

[andrewnicols]

Pinging @paulholden FYI

[andrewnicols]

Thanks for working on this @NeillM :)

[NeillM]

Since I'm having my first foray into using the report builder API I might as well.

When you get your head around what you need to do it is a very nice system.