Phab refused to upload the diff for non-UTF8 file, so I had to upload it as binary.

I can't view this file, neither download it as it seems to be a binary file.

I've uploaded the patch there: http://arrowd.name/doc.diff

It is quite inconvenient that Phabricator can't be used to review such changes. What's the rationale for using KOI8-R encoding? Can it be switched to UTF-8?

@wblock was working on converting the docs to UTF-8, but efforts have stalled at the moment.
Ideally, if you want to make changes to the Russian translation, you'd find someone (other than me) who can mentor you for that language as a doc committer (or ask him/her to review and commit it).
I can only review the change for DocBook itself, but I can't comment on the language-specific parts. You could ask on the freebsd-doc mailing list if anyone is willing to help for that language. Thanks.

Copying from -docs:

Talking about http://arrowd.name/doc.diff: indentation in the last chunk looks dubious for me. Otherwise looks good.

I've fixed the indentation and reuploaded the patch. @bcr, can you commit it?

Sure, I'll do so soon.
Thanks for the patch!