Tidy up usage ping and cohorts docs

doc/user/admin_area/settings/usage_statistics.md

@@ -25,8 +25,8 @@ for all signed in users.
 ## Usage ping
 
 > [Introduced][ee-557] in GitLab Enterprise Edition 8.10. More statistics
-[were added][ee-735] in GitLab Enterprise Edition 8.12. [Moved to CE][ce-23361]
-in GitLab 9.1.
+[were added][ee-735] in GitLab Enterprise Edition
+8.12. [Introduced to GitLab Community Edition][ce-23361] in 9.1.
 
 GitLab Inc. can collect non-sensitive information about how GitLab users
 use their GitLab instance upon the activation of a ping feature
@@ -35,13 +35,12 @@ located in the admin panel (`/admin/application_settings`).
 You can see the **exact** JSON payload that your instance sends to GitLab
 in the "Usage statistics" section of the admin panel.
 
-Nothing qualitative is collected. Only quantitative. That means no project name,
-author name, nature of comments, name of labels, etc.
+Nothing qualitative is collected. Only quantitative. That means no project
+names, author names, comment bodies, names of labels, etc.
 
-The usage ping is sent for the following reasons:
-
-- to have a better understanding on how our users use our product,
-- to be more data driven when creating or changing features.
+The usage ping is sent in order for GitLab Inc. to have a better understanding
+of how our users use our product, and to be more data-driven when creating or
+changing features.
 
 The total number of the following is sent back to GitLab Inc.:
 
@@ -81,7 +80,7 @@ For example: `"mattermost_enabled":true"`.
 
 More data will be added over time. The goal of this ping is to be as light as
 possible, so it won't have any performance impact on your installation when
-calculation is made.
+the calculation is made.
 
 ### Deactivate the usage ping
 

doc/user/admin_area/user_cohorts.md

@@ -4,7 +4,7 @@
 - [Introduced][ce-23361] in GitLab 9.1.
 
 As a benefit of having the [usage ping active](settings/usage_statistics.md),
-GitLab lets you analyze the user's activities of your GitLab installation.
+GitLab lets you analyze the users' activities of your GitLab installation.
 Under [LINK], when the usage ping is active, GitLab will show the monthly
 cohorts of new users and their activities over time.
 
@@ -14,13 +14,13 @@ user cohorts.
 ![User cohort example](img/cohorts.png)
 
 For the cohort of June 2016, 163 users have been created on this server. One
-month after, in July 2016, 155 users (or 95% of the June cohort) are still
-active. Two months after, 139 users (or 85%) are still active. 9 months after,
+month later, in July 2016, 155 users (or 95% of the June cohort) are still
+active. Two months later, 139 users (or 85%) are still active. 9 months later,
 we can see that only 6% of this cohort are still active.
 
 How do we measure the activity of users? GitLab considers a user active if:
 * the user signs in
-* the user has a git activity (whether push or pull).
+* the user has Git activity (whether push or pull).
 
 ### Setup