[clang][bytecode][NFC] Surround Pointer diagram in \verbatim (llvm#158550)

See if this fixes the documentation.

Author: tbaederr

clang/lib/AST/ByteCode/Pointer.h

@@ -75,7 +75,7 @@ enum class Storage { Block, Int, Fn, Typeid };
 /// data the pointer decribes can be found at
 /// Pointee->rawData() + Pointer.Offset.
 ///
-///
+/// \verbatim
 /// Pointee                      Offset
 /// │                              │
 /// │                              │
@@ -87,6 +87,7 @@ enum class Storage { Block, Int, Fn, Typeid };
 ///                      │
 ///                      │
 ///                     Base
+/// \endverbatim
 class Pointer {
 private:
   static constexpr unsigned PastEndMark = ~0u;