docs(MAINTAINING): add section for syncing VS Code upstream

Author: jsjoeio

docs/MAINTAINING.md

@@ -2,26 +2,28 @@
 <!-- DON'T EDIT THIS SECTION, INSTEAD RE-RUN doctoc TO UPDATE -->
 # Maintaining
 
-- [Team](#team)
-  - [Onboarding](#onboarding)
-  - [Offboarding](#offboarding)
-- [Workflow](#workflow)
-  - [Milestones](#milestones)
-  - [Triage](#triage)
-  - [Project boards](#project-boards)
-- [Versioning](#versioning)
-- [Pull requests](#pull-requests)
-  - [Merge strategies](#merge-strategies)
-  - [Changelog](#changelog)
-- [Releases](#releases)
-  - [Publishing a release](#publishing-a-release)
-    - [AUR](#aur)
-    - [Docker](#docker)
-    - [Homebrew](#homebrew)
-    - [npm](#npm)
-- [Testing](#testing)
-- [Documentation](#documentation)
-  - [Troubleshooting](#troubleshooting)
+- [Maintaining](#maintaining)
+  - [Team](#team)
+    - [Onboarding](#onboarding)
+    - [Offboarding](#offboarding)
+  - [Workflow](#workflow)
+    - [Milestones](#milestones)
+    - [Triage](#triage)
+    - [Project boards](#project-boards)
+  - [Versioning](#versioning)
+  - [Pull requests](#pull-requests)
+    - [Merge strategies](#merge-strategies)
+    - [Changelog](#changelog)
+  - [Releases](#releases)
+    - [Publishing a release](#publishing-a-release)
+      - [AUR](#aur)
+      - [Docker](#docker)
+      - [Homebrew](#homebrew)
+      - [npm](#npm)
+  - [Syncing with Upstream VS Code](#syncing-with-upstream-vs-code)
+  - [Testing](#testing)
+  - [Documentation](#documentation)
+    - [Troubleshooting](#troubleshooting)
 
 <!-- END doctoc generated TOC please keep comment here to allow auto update -->
 
@@ -126,8 +128,7 @@ the issue.
 
 ### Merge strategies
 
-For most things, we recommend the **squash and merge** strategy. If you're
-updating `lib/vscode`, we suggest using the **rebase and merge** strategy. There
+For most things, we recommend the **squash and merge** strategy. There
 may be times where **creating a merge commit** makes sense as well. Use your
 best judgment. If you're unsure, you can always discuss in the PR with the team.
 
@@ -215,6 +216,17 @@ We publish code-server as a npm package [here](https://www.npmjs.com/package/cod
 
 This is currently automated with the release process.
 
+## Syncing with Upstream VS Code
+
+The VS Code portion of code-server lives under [`cdr/vscode`](https://github.com/cdr/vscode). To update VS Code for code-server, follow these steps:
+1. `git checkout -b vscode-update` - Create a new branch locally based off `main`
+2. `git fetch upstream` - Fetch upstream (VS Code)'s latest `main` branch
+3. `git merge upstream/main` - Merge it locally
+   1. If there are merge conflicts, fix them locally
+4. Open a PR merging your branch (`vscode-update`) into `main` and add the code-server review team
+
+Ideally, our fork stays as close to upstream as possible. See the differences between our fork and upstream [here](https://github.com/microsoft/vscode/compare/main...cdr:main).
+
 ## Testing
 
 Our testing structure is laid out under our [Contributing docs](https://coder.com/docs/code-server/latest/CONTRIBUTING#test).