Update link to docs for Strategy

doc/operations/feature_flags.md

@@ -81,7 +81,7 @@ You can apply a feature flag strategy across multiple environments, without defi
 the strategy multiple times.
 
 GitLab Feature Flags use [Unleash](https://docs.getunleash.io/) as the feature flag
-engine. In Unleash, there are [strategies](https://docs.getunleash.io/activation_strategy/)
+engine. In Unleash, there are [strategies](https://docs.getunleash.io/user_guide/activation_strategy)
 for granular feature flag controls. GitLab Feature Flags can have multiple strategies,
 and the supported strategies are:
 
@@ -96,8 +96,7 @@ and selecting **Edit** (**{pencil}**).
 
 ### All users
 
-Enables the feature for all users. It uses the [`default`](https://docs.getunleash.io/activation_strategy/#default)
-Unleash activation strategy.
+Enables the feature for all users. It uses the Standard (`default`) Unleash activation [strategy](https://docs.getunleash.io/user_guide/activation_strategy#standard).
 
 ### Percent Rollout
 
@@ -105,8 +104,7 @@ Unleash activation strategy.
 
 Enables the feature for a percentage of page views, with configurable consistency
 of behavior. This consistency is also known as stickiness. It uses the
-[`flexibleRollout`](https://docs.getunleash.io/activation_strategy/#flexiblerollout)
-Unleash activation strategy.
+Gradual Rollout (`flexibleRollout`) Unleash activation [strategy](https://docs.getunleash.io/user_guide/activation_strategy#gradual-rollout).
 
 You can configure the consistency to be based on:
 
@@ -134,7 +132,7 @@ Selecting **Random** provides inconsistent application behavior for individual u
 ### Percent of Users
 
 Enables the feature for a percentage of authenticated users. It uses the Unleash activation strategy
-[`gradualRolloutUserId`](https://docs.getunleash.io/activation_strategy/#gradualrolloutuserid).
+[`gradualRolloutUserId`](https://docs.getunleash.io/user_guide/activation_strategy#gradual-rollout).
 
 For example, set a value of 15% to enable the feature for 15% of authenticated users.
 
@@ -156,8 +154,7 @@ ID for the feature to be enabled. See the [Ruby example](#ruby-application-examp
 > - [Updated](https://gitlab.com/gitlab-org/gitlab/-/issues/34363) to be defined per environment in GitLab 12.6.
 
 Enables the feature for a list of target users. It is implemented
-using the Unleash [`userWithId`](https://docs.getunleash.io/activation_strategy/#userwithid)
-activation strategy.
+using the Unleash UserIDs (`userWithId`) activation [strategy](https://docs.getunleash.io/user_guide/activation_strategy#userids).
 
 Enter user IDs as a comma-separated list of values (for example,
 `user@example.com, user2@example.com`, or `username1,username2,username3`, and so on). Note that
@@ -187,8 +184,7 @@ To search for code references of a feature flag:
 > [Introduced](https://gitlab.com/gitlab-org/gitlab/-/issues/35930) in GitLab 13.1.
 
 Enables the feature for lists of users created [in the Feature Flags UI](#create-a-user-list), or with the [Feature Flag User List API](../api/feature_flag_user_lists.md).
-Similar to [User IDs](#user-ids), it uses the Unleash [`userWithId`](https://docs.getunleash.io/activation_strategy/#userwithid)
-activation strategy.
+Similar to [User IDs](#user-ids), it uses the Unleash UsersIDs (`userWithId`) activation [strategy](https://docs.getunleash.io/user_guide/activation_strategy#userids).
 
 It's not possible to *disable* a feature for members of a user list, but you can achieve the same
 effect by enabling a feature for a user list that doesn't contain the excluded users.