As any app for Jira Cloud, you can install the app via the Jira admin menu.
Log into your Jira instance as an admin.
Click on “Apps > Manage apps” in the header menu.
Click on “Find new apps” on the right navigation.
Search for “Mermaid Charts & Diagrams for Jira” and select it.
Click on “Try it free” to install the app.
Mermaid Charts & Diagrams for Jira provides a app that allows you to add allows you to add beautiful diagrams define with a textual descriptions. A documentation of the textual description can be found here https://mermaid-js.github.io/mermaid. To add a diagram to an issue, select the app as shown in the screenshot below.
In the app, enter the textual description of the diagram and click “save”.