Update Skia gardener doc to mention Flutter Engine Sherriff chat room

Change-Id: Idac150743afd17dbff192df5365a9bc0a0da5bab
No-Try: true
Docs-Preview: https://skia.org/?cl=417056
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/417056
Reviewed-by: Robert Phillips <robertphillips@google.com>
Commit-Queue: Robert Phillips <robertphillips@google.com>
Auto-Submit: Adlai Holler <adlai@google.com>

site/docs/dev/gardening/_index.md

@@ -9,9 +9,14 @@ weight: 8
 
 - [What does a Skia Gardener do?](#what_is_a_skia_gardener)
   - [Skia tree](#skia_tree)
+  - [Triage](#triage)
+  - [Blamer](#blamer)
   - [AutoRollers](#autorollers)
   - [Gold and Perf](#gold_and_perf)
   - [Documentation](#skia_gardener_doc)
+- [Preparing for your rotation](#preparations)
+  - [Useful bookmarks](#useful_bookmarks)
+  - [Chat rooms](#chat_rooms)
 - [View current and upcoming rotations](#view_current_upcoming_rotations)
 - [How to swap rotation shifts](#how_to_swap)
 - [Tips for Skia Gardeners](#tips)
@@ -133,6 +138,28 @@ vacation), please get approval from the person you want to swap with and
 directly make the swap via the
 [rotations page](https://rotations.corp.google.com/rotation/4699606003744768).
 
+<a name="preparations"></a> Preparing for your rotation
+
+---
+
+<a name="useful_bookmarks"></a>
+
+### Useful bookmarks
+
+- [The Chromium main console](https://ci.chromium.org/p/chromium/g/main/console).
+- [The Flutter engine console](https://ci.chromium.org/p/flutter/g/engine/console).
+- [Skia client search](https://brianosman.users.x20web.corp.google.com/www/skia-client-search.html),
+  a tool for searching the codebases of all skia clients at once.
+
+<a name="chat_rooms"></a>
+
+### Chat rooms
+
+- [Flutter Engine Sherriff](https://chat.google.com/room/AAAAm69vf-M) room to
+  watch for Flutter issues that are caused by Skia bugs or need assistance from
+  our team.
+
+
 <a name="tips"></a> Tips for Skia Gardeners
 
 ---