Table entry in cl_intel_split_work_group_barrier is too big

Documentation build errors on `out/pdf/extensions.pdf` with:
```
asciidoctor: ERROR: the table cell on page 180 has been truncated; Asciidoctor PDF does not support table cell content that exceeds the height of a single page
```

The offending SPEC is here:
https://github.com/KhronosGroup/OpenCL-Docs/blob/6191cbee88d98a785b2ee1cd8eff7a0fbfe84d14/extensions/cl_intel_split_work_group_barrier.asciidoc?plain=1#L104-L133

In practice if using a parallel build it is not an issue, since all pdfs will be built either way. The entry in the table gets truncated.

If using a serial build, following pdfs will not be built, and build has to be rerun which will finish building the remaining pdfs (since `out/pdf/extensions.pdf` has been built even with the error).

Inspect extensions/cl_intel_split_work_group_barrier.asciidoc around lines 104-133 and reproduce the documentation build for out/pdf/extensions.pdf. Adjust the oversized table entry so the PDF has no truncated cell, then verify that a serial build completes without requiring a rerun.

Written by the indexing model from the issue text.