docs: update extensions and build

docs/howto-build.md

@@ -6,7 +6,8 @@
   - [Linux](#dependencies-linux)
   - [MacOS](#dependencies-macos)
   - [Windows](#dependencies-windows)
-- [Build Scripts](#build-scripts)
+- [Build for Development](#build-dev)
+- [Build for CI/Downstream](#build-ci)
 - [Build Snap](#build-snap)
 - [Patch Update Process](#patch-update-process)
   - [Semi-Automated](#patch-update-process-semiauto)
@@ -14,10 +15,11 @@
 
 ## <a id="dependencies"></a>Dependencies
 
-- node 20.14
+- node 20.18
 - jq
 - git
 - python3 3.11
+- rustup
 
 ### <a id="dependencies-linux"></a>Linux
 
@@ -48,7 +50,7 @@ see [the common dependencies](#dependencies)
 - [WiX Toolset](http://wixtoolset.org/releases/)
 - 'Tools for Native Modules' from the official Node.js installer
 
-## <a id="build-scripts"></a>Build Scripts
+## <a id="build-dev"></a>Build for Development
 
 A build helper script can be found at `dev/build.sh`.
 
@@ -72,6 +74,31 @@ The script `dev/build.sh` provides several flags:
 - `-p`: generate the packages/assets/installers
 - `-s`: do not retrieve the source code of Visual Studio Code, it won't delete the existing build
 
+## <a id="build-ci"></a>Build for CI/Downstream
+
+Here is the base script to build VSCodium:
+
+```bash
+# Export necessary environment variables
+export SHOULD_BUILD="yes"
+export SHOULD_BUILD_REH="no"
+export CI_BUILD="no"
+export OS_NAME="linux"
+export VSCODE_ARCH="${vscode_arch}"
+export VSCODE_QUALITY="stable"
+export RELEASE_VERSION="${version}"
+
+. get_repo.sh
+. build.sh
+```
+
+To go further, you should look at how we build it:
+- Linux: https://github.com/VSCodium/vscodium/blob/master/.github/workflows/stable-linux.yml
+- macOS: https://github.com/VSCodium/vscodium/blob/master/.github/workflows/stable-macos.yml
+- Windows: https://github.com/VSCodium/vscodium/blob/master/.github/workflows/stable-windows.yml
+
+The `./dev/build.sh` script is for development purpose and must be avoided for a packaging purpose.
+
 ## <a id="build-snap"></a>Build Snap
 
 ```
@@ -103,13 +130,12 @@ review-tools.snap-review --allow-classic codium*.snap
 ## <a id="patch-update-process-manual"></a>Manual
 
 - run `./dev/build.sh`, if a patch is failing then,
-- open `vscode` directory in **VSCodium**
-- revert all changes
-- run `git apply --reject ../patches/<name>.patch`
+- run `./dev/patch.sh <name>.patch` where `<name>.patch` is the failed patch
+- open `vscode` directory in a new **VSCodium**'s window
 - fix all the `*.rej` files
 - run `npm run watch`
 - run `./script/code.sh` until everything is ok
-- run `git diff > ../patches/<name>.patch`
+- go back to the command line running `./dev/patch.sh`, press `enter` to validate the changes and it will update the patch
 
 ### <a id="icons"></a>icons/build_icons.sh