PolyGerrit: Mention style guide used in the project

Change-Id: I669f0ec7fd11bd2acf4b5ee27d0772c039ce6d6b

polygerrit-ui/README.md

diff --git a/polygerrit-ui/README.md b/polygerrit-ui/README.md
index cbc2660..dc0a731 100644
--- a/polygerrit-ui/README.md
+++ b/polygerrit-ui/README.md
@@ -65,3 +65,9 @@
 ```sh
 WCT_ARGS='-p --some-flag="foo bar"' buck test --no-results-cache --include web
 ```
+
+## Style guide
+
+We follow the [Google JavaScript Style Guide](https://google.github.io/styleguide/javascriptguide.xml)
+with a few exceptions. When in doubt, remain consistent with the code around you.
+