Docs: Add use cases for linked epics

What does this MR do?

Adds use case topics to https://docs.gitlab.com/ee/user/group/epics/linked_epics.html based on Epics linked items widget - update docs with us... (#407465 - closed).

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doc/user/group/epics/linked_epics.md

@@ -23,7 +23,7 @@ To manage linked epics through our API, see [Linked epics API](../../../api/link
 You can use linked epics to solve several planning and coordination challenges.
 The following examples show how linked epics help teams work together more effectively.
 
-### Cross-functional initiatives with linked epics
+### Cross-functional initiatives
 
 Use linked epics to coordinate work between multiple teams and track interdependent deliverables.
 When teams work together on a large initiative, each team can manage their own epic while maintaining
@@ -48,9 +48,9 @@ When you link epics across groups:
 - Teams can see related work without switching between groups.
 - Status updates automatically flow between linked epics.
 
-### Dependency management with linked epics
+### Dependency management
 
-Use linked epics to track work that depends on other work being completed first.
+Use linked epics to manage and track work dependencies.
 When development can't begin until infrastructure changes are complete, linked epics help teams
 manage these dependencies.
 
@@ -73,7 +73,7 @@ When you link epics to show dependencies:
 - Teams know when they can start their work.
 - Status updates flow automatically between epics.
 
-### Higher-level planning with linked epics
+### Higher-level planning
 
 Use linked epics to connect short-term execution with long-term planning.
 When managing a series of releases, you can organize high-level goals and track individual feature
@@ -90,7 +90,7 @@ By linking these epics:
 - Teams stay focused on current work while seeing future plans.
 - Stakeholders can monitor both granular and high-level progress.
 
-This structure helps teams maintain momentum on current work while keeping sight of broader goals.
+This structure helps teams progress on current work while maintaining broader goals.
 
 When you link epics for planning: