Regex line: ^(.*[^\n:]{1}):{2}([^\n:]{1}.*)

1. Create a file called test.md
2. Paste the following contents into the file:

This is how to use::Remnote single-line style
The script won't see things outside of it.
You can have::multiple notes in the same file

3. In the plugin settings, paste the Regex line into the 'Custom Regexps' field associated with 'Basic'
4. Ensure that the 'Regex' option is checked
5. Click the Anki icon on the ribbon to run the plugin

3. Run the script, and check 'Config' to open up the config file:
   
4. Navigate to the "Custom Regexps" section
5. Change the line

Basic =  

to

Basic = ^(.*[^\n:]{1}):{2}([^\n:]{1}.*)

6. Save the config file
7. Run the script on the file, with 'Regex' checked:
   

8. You should see these cards in Anki: