Fixes "introduced in..." syntax

doc/ci/variables/README.md

@@ -108,7 +108,7 @@ future GitLab releases.**
 | **GITLAB_USER_NAME**            | 10.0   | all    | The real name of the user who started the job |
 | **RESTORE_CACHE_ATTEMPTS**      | 8.15   | 1.9    | Number of attempts to restore the cache running a job |
 
-## 9.0 Renaming
+## GitLab 9.0 renaming
 
 To follow conventions of naming across GitLab, and to further move away from the
 `build` term and toward `job` CI variables have been renamed for the 9.0
@@ -137,7 +137,7 @@ future GitLab releases.**
 ## `.gitlab-ci.yml` defined variables
 
 NOTE **Note:**
-This feature requires GitLab Runner 0.5.0 or higher and GitLab CI 7.14 or higher.
+This feature requires GitLab Runner 0.5.0 or higher and GitLab 7.14 or higher.
 
 GitLab CI allows you to add to `.gitlab-ci.yml` variables that are set in the
 build environment. The variables are hence saved in the repository, and they
@@ -176,8 +176,7 @@ script:
 
 ## Variables
 
-NOTE: **Note:**
-Group-level variables were added in GitLab 9.4.
+> Group-level variables were introduced in GitLab 9.4.
 
 CAUTION: **Important:**
 Be aware that variables are not masked, and their values can be shown
@@ -206,8 +205,7 @@ Once you set them, they will be available for all subsequent pipelines. You can
 
 ### Protected variables
 
->**Notes:**
-This feature requires GitLab 9.3 or higher.
+> Introduced in GitLab 9.3.
 
 Variables could be protected. Whenever a variable is
 protected, it would only be securely passed to pipelines running on the
@@ -228,8 +226,7 @@ Variables can be specified for a single pipeline run when a [manual pipeline](..
 
 ## Deployment variables
 
-NOTE: **Note:**
-This feature requires GitLab CI 8.15 or higher.
+> Introduced in GitLab 8.15.
 
 [Project services](../../user/project/integrations/project_services.md) that are
 responsible for deployment configuration may define their own variables that
@@ -490,7 +487,7 @@ export CI_REGISTRY_PASSWORD="longalfanumstring"
 
 ## Variables expressions
 
-> Variables expressions were added in GitLab 10.7.
+> Introduced in GitLab 10.7.
 
 It is possible to use variables expressions with only / except policies in
 `.gitlab-ci.yml`. By using this approach you can limit what jobs are going to