[clang-doc] Removed unused method in the Info class

clang-tools-extra/clang-doc/Representation.h

struct Info {
 
   llvm::SmallString<16> extractName() const;
 
   /// Returns the file path for this Info relative to CurrentPath.
   llvm::SmallString<64> getRelativeFilePath(const StringRef &CurrentPath) const;
 
   /// Returns the basename that should be used for this Info.
   llvm::SmallString<16> getFileBaseName() const;
-
-  // Returns a reference to the parent scope (that is, the immediate parent
-  // namespace or class in which this decl resides).
-  llvm::Expected<Reference> getEnclosingScope();
 };
 
 // Info for namespaces.
 struct NamespaceInfo : public Info {
   NamespaceInfo(SymbolID USR = SymbolID(), StringRef Name = StringRef(),
                 StringRef Path = StringRef());
 
   void merge(NamespaceInfo &&I);