docs(lsphp): the build assertion probes with -i, not -m

The comment describing the assertion still said 'lsphp -m | grep' while the
code correctly uses -i. That is the exact trap documented three lines below --
lsphp is the LSAPI SAPI and answers -m by printing usage and exiting 0, so an
-m based check never matches and never fails. Leaving the comment wrong would
invite someone to 'restore' it.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

Dockerfile.lsphp

@@ -87,7 +87,7 @@ RUN bash -c 'set -e; \
 ## cac_path_parity.from/.to mapping, so it is safe in any context (including
 ## wp-cli runs, where $_SERVER carries no filesystem paths).
 ##
-## The trailing `lsphp -m | grep` is a BUILD-TIME ASSERTION: if the .so fails to
+ grep` is a BUILD-TIME ASSERTION| grep` is a BUILD-TIME ASSERTION: if the .so fails to
 ## load (ABI drift after a base-image PHP bump, bad build) the image build fails
 ## here rather than shipping a sidecar that silently lost path parity.
 ## NOTE: probe lsphp with `-i` ONLY. The lsphp binary is the LSAPI SAPI, not the