As a content editor, I want the dropdown list of document types in the document detail page alphabetized, so that I know where to look when I make a selection (especially if the list grows)

[kseniaryzhova]

Is your feature request related to a problem? Please describe.
We just added a new document type, and we may continued to do so in the future. The type is "credit instrument or private receipt" but appears at the end of the list after "state document" and "letter" etc. I'm assuming these are just in the order we added them.

Describe the solution you'd like
Please alphabetize the dropdown list of document types (in the document detail page) so that finding the correct type is easier, especially if the list grows.