[clang-tools-extra] [clang-tidy][docs] Add documentation for Clang-Tidy Automation (PR #153166)

[Baranov Victor via cfe-commits]

================
@@ -331,6 +331,106 @@ An overview of all the command-line options:
         some-check.SomeOption: 'some value'
       ...
 
+Clang-Tidy Automation
+=====================
+
+:program:`clang-tidy` can analyze multiple source files by specifying them on the
+command line or by using a compilation database. For larger projects, automation
+scripts provide additional functionality like parallel execution and integration
+with version control systems.
+
+Running Clang-Tidy in Parallel
+-------------------------------
+
+:program:`clang-tidy` can process multiple files sequentially, but for projects
+with many source files, the :program:`run-clang-tidy.py` script provides parallel
+execution to significantly reduce analysis time. This script is included with
+clang-tidy and runs :program:`clang-tidy` over all files in a compilation database
+concurrently.
----------------
vbvictor wrote:

```suggestion
clang-tidy and runs :program:`clang-tidy` over all files in a compilation database
or a specified path concurrently.
```

https://github.com/llvm/llvm-project/pull/153166