[llvm] [RemoveDIs][NFC] Update docs to reflect new class structure (PR #85109)

[J. Ryan Stinnett via llvm-commits]

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@@ -40,13 +40,15 @@ This will all happen transparently without needing to think about it!
 
 ## What exactly have you replaced debug intrinsics with?
 
-We're using a dedicated C++ class called `DPValue` to store debug info, with a one-to-one relationship between each instance of a debug intrinsic and each `DPValue` object in any LLVM IR program. This class stores exactly the same information as is stored in debugging intrinsics. It also has almost entirely the same set of methods, that behave in the same way:
+We're using a dedicated C++ class called `DbgRecord` to store debug info, with a one-to-one relationship between each instance of a debug intrinsic and each `DbgRecord` object in any LLVM IR program; these `DbgRecord`s are represented in the IR as non-instruction debug records, as described in the [Source Level Debugging](https://llvm.org/docs/SourceLevelDebugging.html#debug-records) document. This class has a set of subclasses that store exactly the same information as is stored in debugging intrinsics. Each one also has almost entirely the same set of methods, that behave in the same way:
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jryans wrote:

It might be better to use a relative link since versioned LLVM docs are preserved over time, and we'd want this link to point with in the same docs version. (Doxygen is not versioned AFAICT, so those links are okay as-is.)

```suggestion
We're using a dedicated C++ class called `DbgRecord` to store debug info, with a one-to-one relationship between each instance of a debug intrinsic and each `DbgRecord` object in any LLVM IR program; these `DbgRecord`s are represented in the IR as non-instruction debug records, as described in the [Source Level Debugging](SourceLevelDebugging.html#debug-records) document. This class has a set of subclasses that store exactly the same information as is stored in debugging intrinsics. Each one also has almost entirely the same set of methods, that behave in the same way:
```

https://github.com/llvm/llvm-project/pull/85109