[clang] [TySan] Add initial documentation for Type Sanitizer (PR #123595)

[Erich Keane via cfe-commits]

================
@@ -0,0 +1,156 @@
+================
+TypeSanitizer
+================
+
+.. contents::
+   :local:
+
+Introduction
+============
+
+TypeSanitizer is a detector for strict type aliasing violations. It consists of a compiler
----------------
erichkeane wrote:

```suggestion
The TypeSanitizer is a detector for strict type aliasing violations. It consists of a compiler
```

https://github.com/llvm/llvm-project/pull/123595