[llvm] [llvm-debuginfo-analyzer][DOC] Convert 'README.txt' to markdown. (PR #86394)

[J. Ryan Stinnett via llvm-commits]

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+# `llvm-debuginfo-analyzer`
+
+These are the notes collected during the development, review and test.
+They describe limitations, known issues and future work.
+
+### Remove the use of macros in ``LVReader.h`` that describe the ``bumpallocators``.
+**[D137933](https://reviews.llvm.org/D137933#inline-1389904)**
+
+Use a standard (or LLVM) ``map`` with ``typeinfo`` (would need a specialization
+to expose equality and hasher) for the allocators and the creation
+functions could be a function template.
+
+### Use a ``lit test`` instead of a ``unit test`` for the ``logical readers``.
+**[D125783](https://reviews.llvm.org/D125783#inline-1324376)**
+
+As the ``DebugInfoLogicalView`` library is sufficiently exposed via the
+``llvm-debuginfo-analyzer`` tool, follow the LLVM general approach and
+use ``LIT`` tests to validate the ``logical readers``.
----------------
jryans wrote:

```suggestion
use ``lit`` tests to validate the **logical readers**.
```

https://github.com/llvm/llvm-project/pull/86394