This article contains a workaround to use HTML and/or Javascript in a field description in Jira Server/Data Center.  Due to changes made as a result of JRASERVER-70859 - Getting issue details... STATUS Jira 8.7.0 and higher versions no longer ship with this HTML enabled by default on new installs.  It is still possible to make this work in later versions, however a Jira System Administrator will need to turn ON the option called Enable HTML in custom fields descriptions and list item values.  See Configuring Jira application options for details on this setting.

More information about this change can be found in https://confluence.atlassian.com/jirasoftware/jira-software-8-7-x-upgrade-notes-987138245.html