ensure guide PDF compiles with russian characters

docs/guide-ru/images

+../guide/images/
\ No newline at end of file

docs/guide/tutorial-i18n.md

@@ -29,7 +29,9 @@ Target language is what's currently used. It's defined in application configurat
 return [
     'id' => 'applicationID',
     'basePath' => dirname(__DIR__),
-    'language' => 'ru-RU' // ← here!
+    'language' => 'ru-RU' // <- here!
+    // ...
+]
 ```
 
 Later you can easily change it in runtime:
@@ -45,7 +47,7 @@ Format is `ll-CC` where `ll` is  two- or three-letter lowercase code for a langu
 If there's no translation for `ru-RU` Yii will try `ru` as well before failing.
 
 > **Note**: you can further customize details specifying language
-> [as documented in ICU project](http://userguide.icu-project.org/locale#TOC-The-Locale-Concept).
+> [as documented in the ICU project](http://userguide.icu-project.org/locale#TOC-The-Locale-Concept).
 
 Message translation
 -------------------

extensions/apidoc/templates/pdf/GuideRenderer.php

@@ -44,9 +44,6 @@ class GuideRenderer extends \yii\apidoc\templates\html\GuideRenderer
         $fileData = [];
         $chapters = $this->loadGuideStructure($files);
         foreach ($files as $file) {
-            if (basename($file) == 'tutorial-i18n.md') {
-                continue; // TODO avoid i18n tut because of non displayable characters right now. need to fix it.
-            }
             $fileData[basename($file)] = file_get_contents($file);
 //            if (preg_match("/^(.*)\n=+/", $fileData[$file], $matches)) {
 //                $headlines[$file] = $matches[1];

extensions/apidoc/templates/pdf/main.tex

 \documentclass[a4paper,11pt,twoside]{book}
 
 % english and utf8
-%\usepackage[T1]{fontenc}
+\usepackage[T2A]{fontenc}
 \usepackage[utf8]{inputenc}
 %\usepackage[british,russian]{babel}
 \usepackage[british]{babel}
@@ -56,6 +56,7 @@
     literate={-}{-}1,
     %    {\'}{'}1,
     %    {\"}{\"}1
+  extendedchars=false
 }
 
 \lstdefinelanguage{json}{