Fix max_history example

[akelad]

Proposed changes:

• Fix small but important max history mistake

Status (please check what you already did):

• added some tests for the functionality
• updated the documentation
• updated the changelog (please check changelog for instructions)
• reformat files using black (please check Readme for instructions)

[erohmensing]

This is cause it needs to see that there were 2 utter_defaults right?

Also, I think Tom will make you make a changelog file for this 😄

[akelad]

idk, does a docs change like this require a changelog entry? also yes correct, as soon as you have another intent that triggers utter_default, you would need the max history be 5 as well

[erohmensing]

Ah yeah okay that makes sense, that's why i was a bit confused. And i guess the instructions say docs one are for new docs or big reworkings, so i suppose not