Merge pull request #615 from joemcl/patch-2

update intro text

docs/tools/issue-tracking.md

 # Issue-tracking systems
 
-As of 2018 CiviCRM uses three different system for tracking and managing issues (aka tickets). This page offers a brief summary of the systems and helps developers understand when and how to use them.
+As of 2019, CiviCRM uses two different systems for tracking and managing issues (aka tickets) - GitLab and GitHub. Until early 2018, Jira was also used. This page offers a brief summary of the systems and helps developers understand when and how to use them.
 
 
 ## Systems