If you want to add some rich text into the resource introtext, then you can use Redactor for that.
This is disabled by default. To enable it, go to System > System Settings and find the
redactor.introtext system setting. Enable it.
To change what configuration set is used for the introtext, change the
redactor.introtext.configuration_set system setting. Enter the ID of a valid configuration set, which you can find in Extras > Redactor Configuration.
A minimal configuration set, or one with Air Mode enabled, works great with the introtext.