Linux: Update local documentation logic to the new organization of folders under "docs/html"

src/Main/LanguageStrings.h

@@ -28,10 +28,12 @@ namespace VeraCrypt
 
 		bool Exists (const string &key) const { return Map.find (key) != Map.end(); }
 		wstring Get (const string &key) const;
+		string GetPreferredLang () const { return PreferredLang; }
 		void Init ();
 
 	protected:
 		map <string, wstring> Map;
+		string PreferredLang;
 
 	private:
 		LanguageStrings (const LanguageStrings &);