Install built doc to SAGE_DOC

[kwankyu]

This is a solution for https://groups.google.com/g/sage-devel/c/IVo1EI33CyU, alternative to #40798.

With this PR

make doc-html

installs the built doc to the expected location (set by SAGE_DOC). The same with

make doc-pdf

📝 Checklist

• The title is concise and informative.
• The description explains in detail what this PR is about.
• I have linked a relevant issue or discussion.
• I have created tests covering the changes.
• I have updated the documentation and checked the documentation preview.

⌛ Dependencies

[github-actions]

Documentation preview for this PR (built with commit f94487c; changes) is ready! 🎉
This preview will update shortly after each push to this PR.

[antonio-rojas]

IMO it would be better to do this at the meson level (with install-doc-{html,pdf} targets) and then Makefile would just call these targets. That way, other distributions could also make use of it instead of manually copying docs as it is done now.

That being said, this change only affects sage-the-distro so I have no objection as a temporary stopgap.

[tobiasdiez]

where does SAGE_DOC points to on your system, i.e. where do those docs end up in?

[kwankyu]

For sage-the-distro, it is local/share/doc at sage root by default. The Makefile runs after environment variables for sage-the-distro are setup.

[kwankyu]

IMO it would be better to do this at the meson level (with install-doc-{html,pdf} targets) and then Makefile would just call these targets. That way, other distributions could also make use of it instead of manually copying docs as it is done now.

Yes. Then src/doc/meson.build should be modified.

That being said, this change only affects sage-the-distro so I have no objection as a temporary stopgap.

Yes.

[kwankyu]

Strangely, doctrees directory is also copied, in my testing. Let me fix this.

[kwankyu]

There must have been some confusion on my side. I tested again. It works well.

Ready to go.

[kwankyu]

Anything else?

[kwankyu]

Now the built doc is not copied but links to the doc are installed in appropriate places. This works well with the sage-distro.