warn user about calendar color syncing in DAVx5 when changing calendar color

[k4lizen]

Checklist

• I made sure that there are no existing issues - open or closed - to which I could contribute my information.
• I made sure that there are no existing discussions - open or closed - to which I could contribute my information.
• I have read the FAQs inside the app (Menu -> About -> FAQs) and my problem isn't listed.
• I have taken the time to fill in all the required details. I understand that the request will be dismissed otherwise.
• This issue contains only one feature request.
• I have read and understood the contribution guidelines.

Feature description

In etar, when you change a calendar's colors, a warning message pops up:
https://github.com/Etar-Group/Etar-Calendar/blob/52ec9cc5a36505e79a5049e6c11ef50e6cabc2e9/app/src/main/res/values/strings.xml#L784

Changing the color may be reverted when the calendar is synchronized again.\n\nIn DAVx⁵ 'Manage calendar colors' can be disabled to prevent this.

Why do you want this feature?

Seeing this in fossify calendar would have saved me (and you) some significant time. See #1085 (comment) and #1084 (comment) .

Additional information

No response