[clangd] Some minor fixes.

[ilya-biryukov]

LGTM. Many thanks!

clangd/Selection.cpp

-//===--- Selection.h ------------------------------------------------------===//
+//===--- Selection.cpp ----------------------------------------------------===//
 //
 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
 // See https://llvm.org/LICENSE.txt for license information.
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 //
 //===----------------------------------------------------------------------===//
 
 #include "Selection.h"

clangd/refactor/Tweak.h

struct Selection {
     SelectionTree ASTSelection;
     // FIXME: provide a way to get sources and ASTs for other files.
   };
   virtual ~Tweak() = default;
   /// A unique id of the action, it is always equal to the name of the class
   /// defining the Tweak. Definition is provided automatically by
   /// REGISTER_TWEAK.
   virtual const char *id() const = 0;
-  /// Run the first stage of the action. The non-None result indicates that the
-  /// action is available and should be shown to the user. Returns None if the
+  /// Run the first stage of the action. Returns true indicating that the
+  /// action is available and should be shown to the user. Returns false if the
   /// action is not available.
   /// This function should be fast, if the action requires non-trivial work it
   /// should be moved into 'apply'.
   /// Returns true iff the action is available and apply() can be called on it.
   virtual bool prepare(const Selection &Sel) = 0;
   /// Run the second stage of the action that would produce the actual changes.
   /// EXPECTS: prepare() was called and returned true.
   virtual Expected<tooling::Replacements> apply(const Selection &Sel) = 0;

unittests/clangd/SelectionTests.cpp

-//===-- RIFFTests.cpp - Binary container unit tests -----------------------===//
+//===-- SelectionTests.cpp - ----------------------------------------------===//
 //
 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
 // See https://llvm.org/LICENSE.txt for license information.
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 //
 //===----------------------------------------------------------------------===//
 #include "Annotations.h"
 #include "Selection.h"

unittests/clangd/TweakTests.cpp

 //===-- TweakTests.cpp ------------------------------------------*- C++ -*-===//
 //
-//                     The LLVM Compiler Infrastructure
-//
-// This file is distributed under the University of Illinois Open Source
-// License. See LICENSE.TXT for details.
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 //
 //===----------------------------------------------------------------------===//
 
 #include "Annotations.h"
 #include "SourceCode.h"
 #include "TestTU.h"
 #include "refactor/Tweak.h"
 #include "clang/AST/Expr.h"