Document that Chrome Canary is is_chrome_branded

- Chrome for Testing releases are built with `is_official_build` + `is_chrome_for_testing_branded`.
- Regular Chrome releases are built with `is_official_build` + `is_chrome_branded`.
- Chromium builds usually have none of these GN args set.

Any features conditional on `is_chrome_branded` are thus not supported in Chromium nor in CfT.

Bug: none
Change-Id: Ia8ecac55d93e2cca9abcb4fa3220293858cd7e17
Reviewed-on: https://chromium-review.googlesource.com/c/devtools/devtools-frontend/+/6021663
Reviewed-by: Benedikt Meurer <bmeurer@chromium.org>
Commit-Queue: Benedikt Meurer <bmeurer@chromium.org>
Auto-Submit: Mathias Bynens <mathias@chromium.org>

docs/get_the_code.md

@@ -87,7 +87,10 @@ and a separate CL with a proper roll.
 
 ### Run in a pre-built Chromium
 
-You can run a [build](#Build) of DevTools frontend in a pre-built Chromium in order to avoid the expensive Chromium build. For example, you can use the latest version of Chrome Canary, or the downloaded binary in `third_party/chrome`.
+You can run a [build](#Build) of DevTools frontend in a pre-built Chrome or Chromium in order to avoid the expensive build. Options:
+
+- Use the downloaded Chrome for Testing binary in `third_party/chrome`.
+- Use the latest Chrome Canary. This includes any DevTools features that are only available in regular Chrome builds (`is_official_build` + `is_chrome_branded`), such as GenAI-related features.
 
 #### Running from file system