Add reference to sampling doc in heapprofd design. am: bae8193de6
Add reference to sampling doc in heapprofd design. am: bae8193de6

Original change: https://android-review.googlesource.com/c/platform/external/perfetto/+/1717713

Change-Id: I41ecdd7bd1fb1673c928da27ea2afcc85d020024

google/perfetto,google/perfetto,google/perfetto,google/perfetto,google/perfetto,google/perfetto,google/perfetto,google/perfetto