* Remove `es-test-dir` book-scoped variable
* Remove `plugins-examples-dir` book-scoped variable
* Remove `:dependencies-dir:` and `:xes-repo-dir:` book-scoped variables
- In `index.asciidoc`, two variables (`:dependencies-dir:` and `:xes-repo-dir:`) were removed.
- In `sql/index.asciidoc`, the `:sql-tests:` path was updated to fuller path
- In `esql/index.asciidoc`, the `:esql-tests:` path was updated idem
* Replace `es-repo-dir` with `es-ref-dir`
* Move `:include-xpack: true` to few files that use it, remove from index.asciidoc
* Changes for dynamic templates.
* Clarifying language around dynamic:true and dynamic:runtime.
* Clarifying edits and some restructuring.
* Overhauling the Mapping page.
* Incorporating changes from #66911.
* Reworking mapping page to focus on dynamic vs. explicit mapping.
* Reordering to fix test failure.
* Further clarifying mapping page.
* Reordering sections, adding headings to examples, and other clarifications.
* Incorporating review feedback.
* Adding description of for Painless script.