Add language to HTML tags

Sources/Generator/Generators/OverviewPageGenerator.swift

@@ -25,6 +25,7 @@ struct OverviewPageGenerator {
                 sectionUrl: section.sectionUrl(for: language),
                 languageButton: languageButton,
                 page: section)
+            content[.language] = language
             content[.contentClass] = "overview"
             content[.header] = makeHeader(page: section, metadata: metadata, language: language)
             content[.content] = makeContent(section: section, language: language)

Sources/Generator/Generators/PageGenerator.swift

@@ -28,6 +28,7 @@ struct PageGenerator {
             page: page, metadata: metadata, language: language, path: inputContentPath)
 
         var content = [PageTemplate.Key : String]()
+        content[.language] = language
         content[.head] = factory.pageHead.generate(page: page, language: language, includesCode: pageIncludesCode)
         let sectionUrl = page.sectionUrl(for: language)
         content[.topBar] = factory.topBar.generate(sectionUrl: sectionUrl, languageButton: nextLanguage, page: page)

Sources/Generator/Templates/Pages/PageTemplate.swift

@@ -3,6 +3,7 @@ import Foundation
 struct PageTemplate: Template {
 
     enum Key: String, CaseIterable {
+        case language = "LANG"
         case head = "HEAD"
         case topBar = "TOP_BAR"
         case contentClass = "CONTENT_CLASS"