docs: add pagination pattern to Effective Gno

[Kouteki]

Current state

Users have difficulty understanding clear, idiomatic Gno code when it comes to pagination and usage of the AVL tree.

Desired state

Users can read on using pagination best practices on Effective Gno

Misc

Referenced comment

[wyhaines]

The tl;dr is that I 100% agree that this would be a great resource to have. I've spent a lot of time in the past 5-6 weeks writing Gno code, in part to start trying to absorb some of these differences. Having the little things like the comment referenced above clearly documented would be a godsend for people who are trying to attain a high level of competency with Gno.

[leohhhn]

We will have a much easier pagination system for AVL with the PR below; currently blocked on #2876. Still agree we can add to Effective Gno, as a subitem of the AVL section

• feat: add p/avl/pager #2584