[windows] Add instructions for building mini_installer

Change-Id: I5047acb2f36d6aac6eec75e11848e22de26b550f
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5713610
Commit-Queue: Greg Thompson <[email protected]>
Reviewed-by: Aaron Leventhal <[email protected]>
Auto-Submit: Greg Thompson <[email protected]>
Commit-Queue: Aaron Leventhal <[email protected]>
Cr-Commit-Position: refs/heads/main@{#1328135}
diff --git a/docs/windows_build_instructions.md b/docs/windows_build_instructions.md
index fc45b7d..d722a67 100644
--- a/docs/windows_build_instructions.md
+++ b/docs/windows_build_instructions.md
@@ -435,6 +435,19 @@
 You can find out more about GoogleTest at its
 [GitHub page](https://github.com/google/googletest).
 
+## Build an Installer
+
+Build the `mini_installer` target to create a self-contained installer. This
+has everything needed to install your browser on a machine.
+
+```shell
+$ autoninja -C out\Default mini_installer
+```
+
+See [//chrome/installer/setup/README.md](../chrome/installer/setup/README.md)
+and [//chrome/installer/mini_installer/README.md](../chrome/installer/mini_installer/README.md)
+for more information.
+
 ## Update your checkout
 
 To update an existing checkout, you can run