[clang-tools-extra] Add clang-tidy external examples (PR #106675)

[via cfe-commits]

https://github.com/MichelleCDjunaidi created https://github.com/llvm/llvm-project/pull/106675

Motivation: Clang has a page where they list out external examples: https://clang.llvm.org/docs/ExternalClangExamples.html. While I was writing an out-of-tree clang-tidy plugin, I wanted such a page to exist also as it would have helped development. This example repo has been useful for me.

>From 08324e3586acb16cbf010fd6013c21f2b5faa64e Mon Sep 17 00:00:00 2001
From: MichelleCDjunaidi <87893361+MichelleCDjunaidi at users.noreply.github.com>
Date: Fri, 30 Aug 2024 14:55:16 +0800
Subject: [PATCH] Add clang-tidy external examples

---
 .../clang-tidy/ExternalClang-TidyExamples.rst | 31 +++++++++++++++++++
 1 file changed, 31 insertions(+)
 create mode 100644 clang-tools-extra/docs/clang-tidy/ExternalClang-TidyExamples.rst

diff --git a/clang-tools-extra/docs/clang-tidy/ExternalClang-TidyExamples.rst b/clang-tools-extra/docs/clang-tidy/ExternalClang-TidyExamples.rst
new file mode 100644
index 00000000000000..735f99b30c7b7d
--- /dev/null
+++ b/clang-tools-extra/docs/clang-tidy/ExternalClang-TidyExamples.rst
@@ -0,0 +1,31 @@
+=======================
+External Clang-Tidy Examples
+=======================
+
+Introduction
+============
+
+This page provides examples of what people have done with clang-tidy that 
+might serve as useful guides (or starting points) to develop your own checks. 
+They may be helpful even for necessary things such as how to write CMakeLists.txt 
+for an out-of-tree plugin of clang-tidy checks.
+
+If you know of (or wrote!) a tool or project using clang-tidy, please post on
+`the Discourse forums (Clang Frontend category)
+<https://discourse.llvm.org/c/clang/6>`_ to have it added.
+(or if you are already a clang-tidy contributor, feel free to directly commit
+additions). Since the primary purpose of this page is to provide examples
+that can help developers, generally they must have code available.
+
+As clang-tidy shares C++ AST Matchers with Clang diagnostics, `External Clang Examples`_ 
+may also be useful to look at.
+
+.. _External Clang Examples: https://clang.llvm.org/docs/ExternalClangExamples.html
+
+https://clang.llvm.org/docs/ExternalClangExamples.html
+
+List of projects and tools
+==========================
+
+`<https://github.com/coveooss/clang-tidy-plugin-examples/tree/main>`_
+    "This folder contains clang-tidy plugins."
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