Update the wording in jira doc. Change the text of the cross reference comment.

app/models/project_services/jira_service.rb

@@ -76,7 +76,7 @@ class JiraService < IssueTrackerService
         url: resource_url(project_path(project))
       },
       entity: {
-        name: noteable_name.humanize,
+        name: noteable_name.humanize.downcase,
         url: entity_url
       }
     }
@@ -127,7 +127,7 @@ class JiraService < IssueTrackerService
     project_url = data[:project][:url]
 
     message = {
-      body: "[#{user_name}|#{user_url}] mentioned #{issue_name} in #{entity_name} of [#{project_name}|#{entity_url}]."
+      body: "[#{user_name}|#{user_url}] mentioned this issue in [a #{entity_name} of #{project_name}|#{entity_url}]."
     }.to_json
 
     send_message(url, message)

doc/integration/jira.md

 # GitLab Jira integration
 
 GitLab can be configured to interact with Jira.
-This integration allows you to connect multiple Jira instances to the GitLab instance by allowing
-every project to setup it's own connection to Jira.
+You can set a default Jira server for all GitLab projects ([see external issue tracker document](external-issue-tracker.md#service-template)) but you can also configure a project to connect to another Jira server than the default one.
 Once the project is connected to Jira, you can reference and close the issues in Jira directly from GitLab.
 
 
@@ -14,18 +13,16 @@ Once the project is connected to Jira, you can reference and close the issues in
 
 ### Referencing Jira Issues
 
-When GitLab project has Jira issue tracker configured and enabled, users will be able to mention Jira issues and GitLab will automatically add a link to the mention. This means that in comments in merge requests and commits referencing an issue, eg. `PROJECT-5`, will add a comment in Jira issue in the format:
+When GitLab project has Jira issue tracker configured and enabled, mentioning Jira issue in GitLab will automatically add a comment in Jira issue with the link back to GitLab. This means that in comments in merge requests and commits referencing an issue, eg. `PROJECT-7`, will add a comment in Jira issue in the format:
 
 
 ```
- USER mentioned PROJECT-5 in PLACE_OF_MENTION LINK_TO_THE_MENTION
+ USER mentioned this issue in LINK_TO_THE_MENTION
 ```
 
-
 * `USER` A user that mentioned the issue. This is the link to the user profile in GitLab.
-* `PROJECT-5` Jira issue that is mentioned.
-* `PLACE_OF_MENTION` Name of the entity where Jira issue was mentioned. Can be commit or merge request.
-* `LINK_TO_THE_MENTION` Link to the origin of mention.
+* `LINK_TO_THE_MENTION` Link to the origin of mention with a name of the entity where Jira issue was mentioned.
+Can be commit or merge request.
 
 
 ![example of mentioning or closing the Jira issue](jira_issue_reference.png)