Add notification to dis-encourage users from using the MISC category

[agrabeli]

We generally would like to refrain from using the MISC category, as that was added as a temporary solution for non-categorized URLs.

Moving forward though, we would ideally want to ensure that all URLs are categorized based on the 30 standardized test list categories (https://github.com/citizenlab/test-lists/blob/master/lists/00-LEGEND-new_category_codes.csv), and that (ideally) no URLs are categorized as MISC.

We should probably be communicating this to Test List Editor users, disencouraging them from categorizing new URLs that they add as "MISC".

Could we add a notification that pops-up when a user categorizes a URL as MISC?

This notification could say something in the lines of:

Please refrain from using the MISC category, as it is only intended for non-categorized URLs.

[agrabeli]

Alternatively, would it be possible/desirable to remove the MISC option from the category drop-down menu in the Test Lists Editor? That way, users would not have the option to select that category code.