[clang][docs] Add all clang-tools-extra

The 'Extra Clang Tools' section does not mention any other clang tool
except clang-tidy. This adds all missing extra tools to sync
documentation between this page and the main page of Extra Clang Tools.

Fixes #148538

Author: weirdsmiley

clang/docs/ClangTools.rst

@@ -97,6 +97,41 @@ linter tool. It provides an extensible framework for building compiler-based
 static analyses detecting and fixing bug-prone patterns, performance,
 portability and maintainability issues.
 
+``clang-include-fixer``
+-----------------------
+
+`clang-include-fixer <https://clang.llvm.org/extra/clang-include-fixer.html>`_
+automates the addition of missing ``#include`` directives in a C++ file. It adds
+missing namespace qualifiers to unidentified symbols when necessary.
+
+``modularize``
+--------------
+
+`modularize <https://clang.llvm.org/extra/modularize.html>`_ is a standalone
+tool that checks whether a set of headers provides the consistent definitions
+required to use modules.
+
+``pp-trace``
+------------
+
+`pp-trace <https://clang.llvm.org/extra/pp-trace.html>`_ is a standalone tool
+that traces preprocessor activity. It’s also used as a test of Clang’s
+PPCallbacks interface. It runs a given source file through the Clang
+preprocessor, displaying selected information from callback functions overridden
+in a PPCallbacks derivation. The output is in a high-level YAML format,
+described in pp-trace Output Format.
+
+``clangd``
+----------
+
+`clangd <https://clangd.llvm.org/>`_ is a language server that can work with
+many editors via a plugin.
+
+``clang-doc``
+-------------
+
+`clang-doc <https://clang.llvm.org/extra/clang-doc.html>`_ is a tool for
+generating C and C++ documentation from source code and comments.
 
 Ideas for new Tools
 ===================