Links to external docs updated, "Russian version only" note inserted where applicable

Sorry, forgot to update the URLs in the documents in the previous commit. Have now reviewed all the links to external documents and updated where appropriate: replaced with the English version if one now exists for the linked documentation, and added a "Russian version only"-type comment wherenever an explicit reference to another document is made (such as the "See also" note).
space before `(Russian version only)` needed