[llvm] [Docs][DebugInfo][RemoveDIs] Document some debug-info transition info (PR #79167)

[J. Ryan Stinnett via llvm-commits]

================
@@ -178,6 +179,10 @@ Optimizations
    referencing, to determine variable locations for debug info in the final
    stages of compilation.
 
+:doc:`RemoveDIsDebugInfo`
+   This is a migration guide describing how to move from debug-info using
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jryans wrote:

```suggestion
   This is a migration guide describing how to move from debug info using

```

https://github.com/llvm/llvm-project/pull/79167