[MBI] Add "[Design Doc] MBI: IsolateScheduler" document and "[Code reading]...

[MBI] Add "[Design Doc] MBI: IsolateScheduler" document and "[Code reading] SequenceManager" document

Add scheduler related documents

Change-Id: Ief971df3c6adaf9a79332e8b0e5090c1745e8661
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2342231
Commit-Queue: Minoru Chikamune <chikamune@chromium.org>
Reviewed-by: Alexander Timin <altimin@chromium.org>
Reviewed-by: Kentaro Hara <haraken@chromium.org>
Reviewed-by: Kouhei Ueno <kouhei@chromium.org>
Cr-Commit-Position: refs/heads/master@{#796663}

third_party/blink/renderer/platform/scheduler/links.md

@@ -3,6 +3,10 @@
 The following is a collection of scheduling-related documentation about the
 Blink Scheduler as well as other schedulers in Chrome.
 
+## 2020
+* [Code reading: SequenceManager](https://docs.google.com/document/d/1VRaKEqqyiLOSrjASnJEKNuEIk0_WTBI913Ir36749bI/edit?usp=sharing)
+* [MBI: IsolateScheduler](https://docs.google.com/document/d/1y-vHkrD1z2RtyWYwT6rJkSLHClYNjDDpUbTtBU7l95A/edit?usp=sharing)
+
 ## 2018
 * [Browser-side scheduling roadmap](https://docs.google.com/document/d/1yxjka3kyKieEWP6gRlLyXVy72DJ5Gc22Nqp9vehFj14/edit)
 * [Browser UI thread scheduler](https://docs.google.com/document/d/1z1BDq9vzcEpkhN9LSPF5XMnZ0kLJ8mWWkNAi4OI7cos/edit)