RFR: 8370154: Update @jls and @jvms taglets to point to local specs dir

[Chen Liang]

On Sat, 8 Nov 2025 01:29:13 GMT, Dan Smith <dlsmith at openjdk.org> wrote:

> Updated the JSpec taglets to use relative links into `../specs/jls` and `../specs/jvms` rather than external links, possible now due to JDK-8370153.
> 
> I was surprised there doesn't seem to be a standard way to get a relative path to the docs root, but I copy/pasted from ToolGuide, and made some tweaks based on failures I saw.
> 
> Tested with 'make docs' and manually confirmed that a handful of different `@jls` and `@jvms` tags are pointing to the right place.

Verified this passes on Oracle's CI.

I tested this patch on my local Linux-targeting OpenJDK WSL (because only Linux is building docs); the JVMS links become dead links in OpenJDK builds, which don't have access to JLS/JVMS, which are proprietary to Oracle. We should probably leave a comment that the dead links are intentional.

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Marked as reviewed by liach (Reviewer).

PR Review: https://git.openjdk.org/jdk/pull/28207#pullrequestreview-3438821864
PR Comment: https://git.openjdk.org/jdk/pull/28207#issuecomment-3506995226