ui: Add Pivot tables design doc to toc am: 07ba9e21ca
ui: Add Pivot tables design doc to toc am: 07ba9e21ca

Original change: https://android-review.googlesource.com/c/platform/external/perfetto/+/1831613

Change-Id: Ice4bdd061a8085c47ed8aa60687e03efc6235993

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