Removed empty Russian file.

src/docs/asciidoc/документация/sdk_ru.adoc

@@ -1,8 +0,0 @@
-= sdk_ru
-:author: 
-:revnumber: 
-:revdate: 1970/01/01 00:00
-:relfileprefix: ../
-:imagesdir: ..
-ifdef::env-github,env-browser[:outfilesuffix: .adoc]
-