add a comment about page size vs bpf ring buffer sizing am: 28f01bb027

Original change: https://android-review.googlesource.com/c/platform/system/bpf/+/2631549

Change-Id: Icd169c9f37692b2acfadd895e0b01ea4315cf830
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>