Within Teamwork Desk you can enable an option to show the 'Last Modified' information on your help docs.

To enable this, click on your profile icon to the top right of the navigation bar and select 'Settings':

In the settings area, select the 'Help Docs' tab:

Within the left pane select 'General Settings':

You will now have the option to enable 'Show date last modified under the 'Basics' options:

Once enabled, each help doc will display the 'Last Modified' details to the top left beneath the help doc name:

Note: When enabling or disabling, remember to scroll to the bottom of the page and choose 'Save'.

For more information see: Help Docs settings