Added RU language support (#467)

library/src/layout/table.rs

@@ -285,6 +285,7 @@ impl LocalName for TableElem {
         match lang {
             Lang::GERMAN => "Tabelle",
             Lang::ITALIAN => "Tabella",
+            Lang::RUSSIAN => "Таблица",
             Lang::ENGLISH | _ => "Table",
         }
     }

library/src/math/mod.rs

@@ -269,6 +269,7 @@ impl LocalName for EquationElem {
         match lang {
             Lang::GERMAN => "Gleichung",
             Lang::ITALIAN => "Equazione",
+            Lang::RUSSIAN => "Уравнение",
             Lang::ENGLISH | _ => "Equation",
         }
     }

library/src/meta/bibliography.rs

@@ -184,6 +184,7 @@ impl LocalName for BibliographyElem {
         match lang {
             Lang::GERMAN => "Bibliographie",
             Lang::ITALIAN => "Bibliografia",
+            Lang::RUSSIAN => "Библиография",
             Lang::ENGLISH | _ => "Bibliography",
         }
     }

library/src/meta/figure.rs

@@ -88,6 +88,7 @@ impl LocalName for FigureElem {
         match lang {
             Lang::GERMAN => "Abbildung",
             Lang::ITALIAN => "Figura",
+            Lang::RUSSIAN => "Рисунок",
             Lang::ENGLISH | _ => "Figure",
         }
     }

library/src/meta/heading.rs

@@ -142,6 +142,7 @@ impl LocalName for HeadingElem {
         match lang {
             Lang::GERMAN => "Abschnitt",
             Lang::ITALIAN => "Sezione",
+            Lang::RUSSIAN => "Раздел",
             Lang::ENGLISH | _ => "Section",
         }
     }

library/src/meta/outline.rs

@@ -181,6 +181,7 @@ impl LocalName for OutlineElem {
         match lang {
             Lang::GERMAN => "Inhaltsverzeichnis",
             Lang::ITALIAN => "Indice",
+            Lang::RUSSIAN => "Содержание",
             Lang::ENGLISH | _ => "Contents",
         }
     }

src/doc.rs

@@ -517,6 +517,7 @@ pub struct Lang([u8; 3], u8);
 impl Lang {
     pub const ENGLISH: Self = Self(*b"en ", 2);
     pub const GERMAN: Self = Self(*b"de ", 2);
+    pub const RUSSIAN: Self = Self(*b"ru ", 2);
     pub const ITALIAN: Self = Self(*b"it ", 2);
 
     /// Return the language code as an all lowercase string slice.