Update documentation for "Lightweight mode" am: 1332f5e780 am: f9d6d8242a am: e484fce5b1
Update documentation for "Lightweight mode" am: 1332f5e780 am: f9d6d8242a am: e484fce5b1

Original change: https://android-review.googlesource.com/c/platform/external/perfetto/+/1874015

Change-Id: I7da7cf2b8b801f281acf9962aba33b3d991920c3

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