diff --git a/.circleci/config.yml b/.circleci/config.yml
index a4fc3995eb5bf7da25724f3d7359bab2976b9d13..287b557239cff17eda72eb8145e31a11479f0b43 100644
--- a/.circleci/config.yml
+++ b/.circleci/config.yml
@@ -235,5 +235,6 @@ workflows:
             - "2.7"
 
             xcode-version:
+            # https://circleci.com/docs/2.0/testing-ios/#supported-xcode-versions
             - "12.3.0"
             - "11.7.0"