Clean up docs for releases, compress img and fix link in app/views

app/views/projects/releases/index.html.haml

@@ -2,4 +2,4 @@
 - page_title _('Releases')
 
 %div{ class: container_class }
-  #js-releases-page{ data: { project_id: @project.id, illustration_path: image_path('illustrations/releases.svg'), documentation_path: help_page_path('user/releases') } }
+  #js-releases-page{ data: { project_id: @project.id, illustration_path: image_path('illustrations/releases.svg'), documentation_path: help_page_path('user/project/releases') } }

doc/user/project/releases.md

 # Releases
 
-> [Introduced][23795] in GitLab 11.7.
+> [Introduced](https://gitlab.com/gitlab-org/gitlab-ce/issues/41766) in GitLab 11.7.
 
-A list of the published Releases are available to everyone.
+Releases mark specific points in a project's development history, communicate
+information about the type of change, and deliver on prepared, often compiled,
+versions of the software to be reused elsewhere. Currently, releases can only be
+created through the API.
 
-Nagivate to Projects > Releases in order to see the list of releases of a project:
-    ![Releases List](img/releases.png)
+Navigate to **Project > Releases** in order to see the list of releases of a project.
+
+![Releases list](img/releases.png)