Document the feature groups

Signed-off-by: Rémy Coutable <remy@rymai.me>

1 files changed, 16 insertions, 2 deletions

diff --git a/doc/development/feature_flags.md b/doc/development/feature_flags.md
index 5c6316b9ac6..cf9636eb6f6 100644
--- a/doc/development/feature_flags.md
+++ b/doc/development/feature_flags.md
@@ -3,5 +3,19 @@
 Starting from GitLab 9.3 we support feature flags via
 [Flipper](https://github.com/jnunemaker/flipper/). You should use the `Feature`
 class (defined in `lib/feature.rb`) in your code to get, set and list feature
-flags. During runtime you can set the values for the gates via the
-[admin API](../api/features.md).
+flags.
+
+During runtime you can set the values for the gates via the
+[features API](../api/features.md) (accessible to admins only).
+
+## Feature groups
+
+Starting from GitLab 9.4 we support feature groups via
+[Flipper groups](https://github.com/jnunemaker/flipper/blob/v0.10.2/docs/Gates.md#2-group).
+
+Feature groups must be defined statically in `lib/feature.rb` (in the `.register_feature_groups` method), but their implementation can obviously be
+dynamic (querying the DB etc.). You can see how the `performance_team` feature
+group for a concrete example.
+
+Once defined in `lib/feature.rb`, you will be able to activate a
+feature for a given feature group via the [`feature_group` param of the features API](../api/features.md#set-or-create-a-feature)